drm/i915: Apply OCD to VLV/CHV DPLL defines

Drop the spurious 'A' from the VLV/CHV ref clock enable define,
and add the "REF" to the VLV ref clock selection bit. Also
s/CLOCK/CLK/ for extra consistency.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>