drm/i915/chv: Pipe select change for DP and HDMI

With additional of pipe C, current 1 bit registers for pipe select
for HDMI and DP are no longer able to gather for 3 pipes. As a result,
new bits location in the same registers are added.

For HDMI, VLV uses bit 30, CHV uses bit 24-25.

For DP, VLV uses bit 30, CHV uses bit 16-17.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Chon Ming Lee <chon.ming.lee@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>