drm/i915: Eliminate the CDCLK_CTL RMW on BXT

All the fields in CDCLK_CTL we don't program should be left at zero, so
let's just get rid of the RMW.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1462995892-32416-14-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Imre Deak <imre.deak@intel.com>
1 file changed