drm/i915: Parametrize CBR_DPLLBMD_PIPE defines

Apply a bit of polish by parametrizing the CBR_DPLLBMD_PIPE defines.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170913140900.6972-3-ville.syrjala@linux.intel.com


Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>