backlight: mbp_nvidia_bl - Fix DMI_SYS_VENDOR for MacBook1,1

Fix DMI_SYS_VENDOR for MacBook1,1.

When the MacBook1,1 came out Apple was still named Apple Computer, I am
not sure if this applies to older MacBook2,1 versions aswell.

Signed-off-by: Steffen Röcker <sroecker@gmail.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>