drm/i915: Remove the "pf" crc source

The "pipe" and "pf" crc sources are in fact the same thing.
Remove the "pf" one.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190214192219.3858-1-ville.syrjala@linux.intel.com


Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>