Fix compilation error in cmd_usb.c

This patch fixes compilation error
cmd_usb.c: In function 'do_usb':
cmd_usb.c:552: error: void value not ignored as it ought to be

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Markus Klotzbuecher <mk@denx.de>
1 file changed