media: video-i2c: add Melexis MLX90640 thermal camera

Add initial support for MLX90640 thermal cameras which output an 32x24
greyscale pixel image along with 2 rows of coefficent data.

Because of this the data outputed is really 32x26 and needs the two rows
removed after using the coefficent information to generate processed
images in userspace.

Signed-off-by: Matt Ranostay <matt.ranostay@konsulko.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>