staging: usbip: clean up checkpatch warnings in usbipd.c

A few whitespace changes allows the file to pass checkpatch --strict
(other than ignoring the CamelCase derived from the USB standard.)

Signed-Off-By: Anthony Foiani <anthony.foiani@gmail.com>

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>