drm/i915: PineView only has LVDS and CRT ports

PineView only has 2 ports for LVDS and CRT. Don't enable other
ports for it.

Cc: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>