drm/i915: Don't program DSPCLK_GATE_D twice on IVB and VLV

We were programming register 0x42020 twice on those platforms. Once
should be enough.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
1 file changed