dcd/dwc2: fix EP0 multi-packet transfer logic

[HiFiPhile]

Describe the PR
There was an issue in edpt_schedule_packets, as ep0_pending = xfer->max_size is set in dcd_edpt_xfer, ep0_pending will become 0.

if (epnum == 0) {
    total_bytes = tu_min16(_dcd_data.ep0_pending[dir], xfer->max_size);
    _dcd_data.ep0_pending[dir] -= total_bytes;
    num_packets = 1;
  } 

The issue didn't broken since we schedule only one control transfer each time.

I've add an option CFG_TUD_EP0_BUFSIZE to allow setting EP0 buffer size individually, tested with DFU examples withCFG_TUD_EP0_BUFSIZE=512

[Copilot]

Pull Request Overview

This PR fixes EP0 multi-packet transfer logic in the DWC2 driver and adds configurable EP0 buffer size support. The issue was in the edpt_schedule_packets function where ep0_pending was incorrectly being set to xfer->max_size instead of the proper endpoint size, causing transfer size calculation errors.

Key changes:

• Added CFG_TUD_EP0_BUFSIZE configuration option for EP0 buffer size
• Fixed EP0 packet scheduling logic to use correct endpoint size
• Enhanced packet transmission handling for single vs multi-packet transfers
• Updated DFU examples with BOS descriptors and Microsoft OS 2.0 compatibility

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/tusb_option.h	Added CFG_TUD_EP0_BUFSIZE configuration option
src/portable/synopsys/dwc2/dcd_dwc2.c	Fixed EP0 transfer logic and improved packet handling
src/device/usbd_control.c	Updated to use new CFG_TUD_EP0_BUFSIZE configuration
examples/device/dfu_runtime/src/usb_descriptors.c	Added BOS descriptor and Microsoft OS 2.0 support
examples/device/dfu/src/usb_descriptors.c	Added BOS descriptor and Microsoft OS 2.0 support