[media] v4l: ti-vpe: Allow usage of smaller images

The minimum width and height for VPE input/output was kept as 128 pixels. VPE
doesn't have a constraint on the image height, it requires the image width to
be at least 16 bytes.

Change the minimum supported dimensions to 32x32. This allows us to de-interlace
qcif content. A smaller image size than 32x32 didn't make much sense, so stopped
at this.

Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>