[media] vivi: fix ENUM_FRAMEINTERVALS implementation

This function never checked if width and height are correct. Add such
a check so the v4l2-compliance tool returns OK again for vivi.

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