backlight: mbp_nvidia_bl: add support for MacBookAir 1,1

Add LCD backlight support for the Intel GMA965 found in the MacBookAir
1,1.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Acked-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>