usb: renesas_usbhs: tidyup for smatch warnings

This patch tidyup below smatch complaint

drivers/usb/renesas_usbhs/mod_host.c +642 usbhsh_queue_done()
	 warn: variable dereferenced before check 'urb' (see line 636)

Special thanks to Dan

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>