Split patch into 2 logical chunks

[Wahib Faizi]

Fix coding style issues detected by checkpatch.pl in usbip_host_driver.c.

v2: Split patch into logical chunks, as suggested by 
    Greg Kroah-Hartman <gregkh at linuxfoundation.org>

[PATCH v2 1/2]
Fix coding style issue "do not use assignment in if condition" 
detected by checkpatch.pl in usbip_host_driver.c.

[PATCH v2 2/2]
Fix coding style issue "line over 80 characters" 
detected by checkpatch.pl in usbip_host_driver.c.