Revert "uvcvideo: prevent speculative execution"

CVE-2017-5753 (revert embargoed)
CVE-2017-5715 (revert embargoed)

This reverts commit ffafbf6a.
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/media/usb/uvc/uvc_v4l2.c

@@ -811,7 +811,6 @@ static int uvc_ioctl_enum_input(struct file *file, void *fh,
 		}
 		pin = iterm->id;
 	} else if (index < selector->bNrInPins) {
-		gmb();
 		pin = selector->baSourceID[index];
 		list_for_each_entry(iterm, &chain->entities, chain) {
 			if (!UVC_ENTITY_IS_ITERM(iterm))