FROMGIT: xhci: Decouple handling an event from checking for unhandled events

Some sequences, will require traversing through the entire event ring
without handling the event TRB.  This is ideal for when secondary
interrupters that are utilized by external entities need to clean up the
interrupter's event rings during halting of the XHCI HCD.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>

Bug: 264371591
(cherry picked from commit edc47759 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git

 usb-next)
Change-Id: I5ade774e65f98f9b6d171df14d75e6ce51f49e3e
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>