media: usb: uvc: remove unnecessary & operation

Now that usb_endpoint_maxp() only returns the lowest
11 bits from wMaxPacketSize, we can remove the &
operation from this driver.

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: <linux-media@vger.kernel.org>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>