drm/i915: Rename the plane_state->main/aux to plane_state->color_plane[]

Make the main/aux surface stuff a bit more generic by using an array
of structures. This will allow us to deal with both the main and aux
surfaces with common code.

Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180907152413.15761-5-ville.syrjala@linux.intel.com
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index a93231c..0c7a046 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -503,11 +503,7 @@ struct intel_plane_state {
 	struct {
 		u32 offset;
 		int x, y;
-	} main;
-	struct {
-		u32 offset;
-		int x, y;
-	} aux;
+	} color_plane[2];
 
 	/* plane control register */
 	u32 ctl;