drm/i915: Clean up skl+ PLANE_POS vs. scaler handling

On skl+ the scaler (when enabled) will take care of the plane output
position. Make the code less ugly by just setting crtc_x/y to 0
when the scaler is enabled.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181101150605.18235-6-ville.syrjala@linux.intel.comReviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/i915/intel_sprite.c

@@ -492,6 +492,12 @@ skl_program_plane(struct intel_plane *plane,
 	if (alpha < 0xff)
 		keymsk |= PLANE_KEYMSK_ALPHA_ENABLE;
 
+	/* The scaler will handle the output position */
+	if (plane_state->scaler_id >= 0) {
+		crtc_x = 0;
+		crtc_y = 0;
+	}
+
 	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
 
 	if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv))
@@ -537,14 +543,10 @@ skl_program_plane(struct intel_plane *plane,
 		I915_WRITE_FW(PLANE_CUS_CTL(pipe, plane_id), cus_ctl);
 	}
 
-	if (plane_state->scaler_id >= 0) {
-		if (!slave)
+	if (!slave && plane_state->scaler_id >= 0)
 		skl_program_scaler(plane, crtc_state, plane_state);
 
-		I915_WRITE_FW(PLANE_POS(pipe, plane_id), 0);
-	} else {
 	I915_WRITE_FW(PLANE_POS(pipe, plane_id), (crtc_y << 16) | crtc_x);
-	}
 
 	I915_WRITE_FW(PLANE_CTL(pipe, plane_id), plane_ctl);
 	I915_WRITE_FW(PLANE_SURF(pipe, plane_id),