device/mtp: queue ZLP when needed

[HiFiPhile]

FIx missing ZLP for IN/OUT data transfers.

Data size tested:
52 (zlp), 114, 116 (zlp), 500 (zlp), 578, 1012 (zlp)

Fix #3430

[Copilot]

Pull request overview

This PR aims to fix missing Zero Length Packet (ZLP) handling for MTP device IN/OUT data transfers. The changes add logic to detect when a ZLP should be queued and implements the queueing mechanism.

Key changes:

• Added ep_sz_fs field to store full-speed endpoint packet size for dynamic ZLP detection
• Modified endpoint initialization order and added endpoint packet size capture
• Implemented ZLP queueing logic based on transfer completion and packet size alignment

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[github-actions]

Size Difference Report

Because TinyUSB code size varies by port and configuration, the metrics below represent the averaged totals across all example builds.

Note: If there is no change, only one value is shown.

Changes >1% in size

file	.text	.rodata	.data	.bss	size	% diff
mtp_device.c	1622 ➙ 1685 (+63)	22	1385 ➙ 1433 (+48)	578	2208 ➙ 2271 (+63)	+2.9%
TOTAL	1622 ➙ 1685 (+63)	22	1385 ➙ 1433 (+48)	578	2208 ➙ 2271 (+63)	+2.9%

Changes <1% in size

No entries.

No changes

file	.text	.rodata	.data	.bss	size	% diff
audio_device.c	2860	0	1250	1688	4543	+0.0%
cdc_device.c	1333	16	20	692	2024	+0.0%
cdc_host.c	6596	487	15	1539	8357	+0.0%
dcd_ch32_usbfs.c	1472	0	0	2444	3916	+0.0%
dcd_ch32_usbhs.c	1648	0	0	448	2096	+0.0%
dcd_ci_fs.c	1925	0	0	1290	3215	+0.0%
dcd_ci_hs.c	1762	0	0	1280	2530	+0.0%
dcd_da146xx.c	3067	0	0	144	3211	+0.0%
dcd_dwc2.c	4188	25	0	263	4474	+0.0%
dcd_eptri.c	2270	0	0	259	2529	+0.0%
dcd_khci.c	1953	0	0	1290	3243	+0.0%
dcd_lpc17_40.c	1470	0	0	648	1794	+0.0%
dcd_lpc_ip3511.c	1463	0	0	264	1639	+0.0%
dcd_mm32f327x_otg.c	1478	0	0	1290	2768	+0.0%
dcd_msp430x5xx.c	1796	0	0	176	1972	+0.0%
dcd_musb.c	2228	0	0	160	2388	+0.0%
dcd_nrf5x.c	2919	0	0	292	3211	+0.0%
dcd_nuc120.c	1093	0	0	78	1171	+0.0%
dcd_nuc121.c	1167	0	0	101	1268	+0.0%
dcd_nuc505.c	0	0	1529	157	1686	+0.0%
dcd_rp2040.c	736	20	580	1029	2365	+0.0%
dcd_rusb2.c	3076	0	0	156	3232	+0.0%
dcd_samd.c	1032	0	0	266	1298	+0.0%
dcd_samg.c	1319	0	0	72	1391	+0.0%
dcd_stm32_fsdev.c	2494	0	0	291	2785	+0.0%
dfu_device.c	744	28	712	184	929	+0.0%
dfu_rt_device.c	157	0	134	0	156	+0.0%
dwc2_common.c	781	29	0	0	797	+0.0%
ecm_rndis_device.c	1037	0	1	2272	3310	+0.0%
ehci.c	2761	0	0	5970	7537	+0.0%
fsdev_common.c	622	0	0	0	622	+0.0%
hcd_ch32_usbfs.c	2484	0	0	498	2982	+0.0%
hcd_ci_hs.c	190	0	0	0	190	+0.0%
hcd_dwc2.c	4880	30	0	512	5422	+0.0%
hcd_khci.c	2442	0	0	449	2891	+0.0%
hcd_musb.c	3073	0	0	157	3230	+0.0%
hcd_pio_usb.c	262	0	240	0	502	+0.0%
hcd_rp2040.c	936	73	420	512	1941	+0.0%
hcd_rusb2.c	2965	0	0	246	3211	+0.0%
hcd_samd.c	2220	0	0	324	2544	+0.0%
hcd_stm32_fsdev.c	3258	0	1	420	3679	+0.0%
hid_device.c	1120	44	997	115	1235	+0.0%
hid_host.c	1206	0	0	1250	2456	+0.0%
hub.c	1235	8	8	29	1268	+0.0%
midi_device.c	1130	0	991	615	1743	+0.0%
midi_host.c	1353	7	7	3740	5097	+0.0%
msc_device.c	2506	108	2274	538	3044	+0.0%
msc_host.c	1589	0	0	394	1984	+0.0%
ncm_device.c	1517	28	1408	5824	7354	+0.0%
ohci.c	1942	0	0	2414	4356	+0.0%
rp2040_usb.c	124	70	574	4	772	+0.0%
rusb2_common.c	0	0	16	0	16	+0.0%
tusb.c	420	0	361	3	421	+0.0%
tusb_fifo.c	890	0	525	0	884	+0.0%
typec_stm32.c	820	8	2	12	842	+0.0%
usbc.c	408	2	16	166	592	+0.0%
usbd.c	3155	57	86	276	3492	+0.0%
usbd_control.c	524	0	474	78	601	+0.0%
usbh.c	4367	60	60	954	5405	+0.0%
usbtmc_device.c	2178	24	70	294	2504	+0.0%
vendor_device.c	636	0	538	476	1111	+0.0%
video_device.c	4402	6	1851	471	4865	+0.0%
TOTAL	111679	1130	15160	45514	159091	+0.0%

[elektroweber]

@HiFiPhile please see my comment here: #3430 (comment)