drm/i915: Disable DC states around GMBUS on GLK

commit 3488d023 upstream.

Prevent the DMC from destroying GMBUS transfers on GLK. GMBUS
lives in PG1 so DC off is all we need.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171208213739.16388-1-ville.syrjala@linux.intel.comReviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
(cherry picked from commit 156961ae)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -1786,6 +1786,7 @@ void intel_display_power_put(struct drm_i915_private *dev_priv,
 	GLK_DISPLAY_POWERWELL_2_POWER_DOMAINS |		\
 	BIT_ULL(POWER_DOMAIN_MODESET) |			\
 	BIT_ULL(POWER_DOMAIN_AUX_A) |			\
+	BIT_ULL(POWER_DOMAIN_GMBUS) |			\
 	BIT_ULL(POWER_DOMAIN_INIT))
 
 #define CNL_DISPLAY_POWERWELL_2_POWER_DOMAINS (		\