usb: fix for parallel transfer deadlock with usb_transfer_sync()

Parallel transfer to same endpoint is not supported and
may cause a deadlock. Adding a check to prevent starting
the transfer if tranfer is already ongoing on same endpoint.

Transfer status was not checked when accessing to transfer
from endpoint callback. Adding status check, to prevent
a double completion.

Fixes #30736

Signed-off-by: Kari Hulkko <kari.m.hulkko@gmail.com>