dcd/musb: extract pipe0_data_stage_done() and fix two EP0 comments

Cleanup from a code-review pass, no behavior change:
- Replace the open-coded "last DATA packet" test (remain_wlength == 0 ||
  len < CFG_TUD_ENDPOINT0_SIZE), duplicated in the edpt0_xfer DATA IN
  arm, pipe0_process_xfer_state_isr, and the DATA OUT drain, with one
  inline pipe0_data_stage_done() so IN and OUT can't drift.
- Correct the xact_len comment (only the IN path reports it; OUT reports
  count0) and the dcd_edpt_stall comment (a deferred SETUP means the old
  transfer ended on the wire, not that its status stage was "seen").

Co-Authored-By: Claude Fable 5 <[email protected]>

0 files changed, 0 insertions, 0 deletions