drm/i915: Implement WaVcpClkGateDisableForMediaReset:ctg, elk

Apparently we need to disable VCP unit clock gating around media reset
on g4x.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 9b3681e..5122254 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1835,6 +1835,10 @@
 #define VF_UNIT_CLOCK_GATE_DISABLE		(1 << 9)
 #define GS_UNIT_CLOCK_GATE_DISABLE		(1 << 7)
 #define CL_UNIT_CLOCK_GATE_DISABLE		(1 << 6)
+
+#define VDECCLK_GATE_D		0x620C		/* g4x only */
+#define  VCP_UNIT_CLOCK_GATE_DISABLE		(1 << 4)
+
 #define RAMCLK_GATE_D		0x6210		/* CRL only */
 #define DEUC			0x6214          /* CRL only */