backlight: mbp_nvidia_bl - add support for older MacBookPro and MacBook 6,1.

Add support for all remaining models not yet present in Linus'/Richard
Purdie's tree nor Evan McClain's patch to finally complete the list.

Signed-off-by: Mario Schwalbe <schwalbe@inf.tu-dresden.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>