media: dt-bindings: Add bindings for panasonic,amg88xx

Define the device tree bindings for the panasonic,amg88xx i2c
video driver.

Cc: devicetree@vger.kernel.org
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Matt Ranostay <matt.ranostay@konsulko.com>
Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>