V4L/DVB (9053): fix buffer overflow in uvc-video

There is a buffer overflow in drivers/media/video/uvc/uvc_ctrl.c:

INFO: 0xf2c5ce08-0xf2c5ce0b. First byte 0xa1 instead of 0xcc
INFO: Allocated in uvc_query_v4l2_ctrl+0x3c/0x239 [uvcvideo] age=13 cpu=1 pid=4975
...

A fixed size 8-byte buffer is allocated, and a variable size field is read
into it; there is no particular bound on the size of the field (it is
dependent on hardware and configuration) and it can overflow [also
verified by inserting printk's.]

The patch attempts to size the buffer to the correctly.

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Laurent Pinchart <laurent.pinchart@skynet.be>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>