drm/imx: remove imx_drm_encoder_get_mux_id

It is replaced by drm_of_encoder_active_port_id.

Suggested-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
diff --git a/drivers/gpu/drm/imx/dw_hdmi-imx.c b/drivers/gpu/drm/imx/dw_hdmi-imx.c
index 063825f..38d9c85 100644
--- a/drivers/gpu/drm/imx/dw_hdmi-imx.c
+++ b/drivers/gpu/drm/imx/dw_hdmi-imx.c
@@ -125,7 +125,7 @@
 static void dw_hdmi_imx_encoder_commit(struct drm_encoder *encoder)
 {
 	struct imx_hdmi *hdmi = container_of(encoder, struct imx_hdmi, encoder);
-	int mux = imx_drm_encoder_get_mux_id(hdmi->dev->of_node, encoder);
+	int mux = drm_of_encoder_active_port_id(hdmi->dev->of_node, encoder);
 
 	regmap_update_bits(hdmi->regmap, IOMUXC_GPR3,
 			   IMX6Q_GPR3_HDMI_MUX_CTL_MASK,