drm/vc4: crtc: Restrict HACT_ACT setup to DSI

The HACT_ACT field only needs to be written to when using a DSI display.
Let's move that setup to our DSI branch to clear a bit the common path.
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/7a93436f97666a2aa025686ef3ff3606de4bec67.1590594512.git-series.maxime@cerno.tech

drivers/gpu/drm/vc4/vc4_crtc.c

@@ -344,7 +344,8 @@ static void vc4_crtc_config_pv(struct drm_crtc *crtc)
 			   (is_dsi ? PV_VCONTROL_DSI : 0));
 	}
 
-	CRTC_WRITE(PV_HACT_ACT, mode->hdisplay * pixel_rep);
+	if (is_dsi)
+		CRTC_WRITE(PV_HACT_ACT, mode->hdisplay * pixel_rep);
 
 	CRTC_WRITE(PV_CONTROL,
 		   VC4_SET_FIELD(format, PV_CONTROL_FORMAT) |