drm/radeon/kms: be more pedantic about the g5 quirk (v2)

I don't think Apple offered any other cards for
this mac, so I doubt this will be an issue, but just
to be on the safe side, check the pci ids as well.

v2: fix spelling in commit message

Reviewed-by: Michel Dänzer <michel@daenzer.net>
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: Joachim Henke <j-o@users.sourceforge.net>
Cc: Michel Dänzer <michel@daenzer.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>