usb: gadget: uvc: add bInterval checking for HS mode

Patch adds extra checking for bInterval passed by configfs.
The 5.6.4 chapter of USB Specification (rev. 2.0) say:
"A high-bandwidth endpoint must specify a period of 1x125 µs
(i.e., a bInterval value of 1)."

The issue was observed during testing UVC class on CV.
I treat this change as improvement because we can control
bInterval by configfs.
Reviewed-by: NPeter Chen <peter.chen@kernel.org>
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NPawel Laszczak <pawell@cadence.com>
Link: https://lore.kernel.org/r/20210308125338.4824-1-pawell@gli-login.cadence.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/function/f_uvc.c

@@ -633,7 +633,12 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
 
 	uvc_hs_streaming_ep.wMaxPacketSize =
 		cpu_to_le16(max_packet_size | ((max_packet_mult - 1) << 11));
-	uvc_hs_streaming_ep.bInterval = opts->streaming_interval;
+
+	/* A high-bandwidth endpoint must specify a bInterval value of 1 */
+	if (max_packet_mult > 1)
+		uvc_hs_streaming_ep.bInterval = 1;
+	else
+		uvc_hs_streaming_ep.bInterval = opts->streaming_interval;
 
 	uvc_ss_streaming_ep.wMaxPacketSize = cpu_to_le16(max_packet_size);
 	uvc_ss_streaming_ep.bInterval = opts->streaming_interval;