USB: FHCI: cq_get() should check kfifo_out()'s return value

Since commit 7acd72eb

 ("kfifo: rename
kfifo_put... into kfifo_in... and kfifo_get... into kfifo_out..."),
kfifo_out() is marked __must_check, and that causes gcc to produce
lots of warnings like this:

  CC      drivers/usb/host/fhci-mem.o
In file included from drivers/usb/host/fhci-hcd.c:34:
drivers/usb/host/fhci.h: In function 'cq_get':
drivers/usb/host/fhci.h:520: warning: ignoring return value of 'kfifo_out', declared with attribute warn_unused_result
...

This patch fixes the issue by properly checking the return value.

Signed-off-by: Anton Vorontsov <avorontsov@mvista.com>
Cc: stable <stable@kernel.org> [.33 and .34]
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>