media: flexcop-usb: fix endpoint type check

Commit d725d20 ("media: flexcop-usb: sanity checking of endpoint
type") tried to add an endpoint type sanity check for the single
isochronous endpoint but instead broke the driver by checking the wrong
descriptor or random data beyond the last endpoint descriptor.

Make sure to check the right endpoint descriptor.

Fixes: d725d20 ("media: flexcop-usb: sanity checking of endpoint type")
Cc: Oliver Neukum <oneukum@suse.com>
Cc: stable@vger.kernel.org	# 5.9
Reported-by: Dongliang Mu <mudongliangabcd@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20220822151027.27026-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: jhovold

drivers/media/usb/b2c2/flexcop-usb.c

@@ -511,7 +511,7 @@ static int flexcop_usb_init(struct flexcop_usb *fc_usb)
 
 	if (fc_usb->uintf->cur_altsetting->desc.bNumEndpoints < 1)
 		return -ENODEV;
-	if (!usb_endpoint_is_isoc_in(&fc_usb->uintf->cur_altsetting->endpoint[1].desc))
+	if (!usb_endpoint_is_isoc_in(&fc_usb->uintf->cur_altsetting->endpoint[0].desc))
 		return -ENODEV;
 
 	switch (fc_usb->udev->speed) {