staging: most: usb: return 0 instead of variable

This patch returns 0 instead of variable in case of invalid parameter
has been passed to function to increase readability.

Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/1590570387-27069-5-git-send-email-christian.gromm@microchip.com


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