usb: renesas_usbhs: fix error return code of usbhsf_pkt_handler()

When __usbhsf_pkt_get() returns NULL to pkt, no error return code of
usbhsf_pkt_handler() is assigned.
To fix this bug, ret is assigned with -EINVAL in this case.
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Link: https://lore.kernel.org/r/20210307090030.22369-1-baijiaju1990@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/renesas_usbhs/fifo.c

@@ -160,8 +160,10 @@ static int usbhsf_pkt_handler(struct usbhs_pipe *pipe, int type)
 	usbhs_lock(priv, flags);
 
 	pkt = __usbhsf_pkt_get(pipe);
-	if (!pkt)
+	if (!pkt) {
+		ret = -EINVAL;
 		goto __usbhs_pkt_handler_end;
+	}
 
 	switch (type) {
 	case USBHSF_PKT_PREPARE: