drm/i915: Remove the "three times for luck" trick from vlv_enable_pll()

VLV DPLL is somewhat sane and doesn't run on luck.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1458052809-23426-7-git-send-email-ville.syrjala@linux.intel.com


Acked-by: Jani Nikula <jani.nikula@intel.com>