xhci: STFU: Don't print event ring dequeue pointer.

Stop printing out the event ring dequeue pointer and status register in
the operational register set.  The host will report an OK status 99% of
the time the interrupt handler is called, and usually when it's really
hosed, a host controller won't even call the interrupt handler.  So the
line is really useless.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>