drm/imx: consolidate bus format variable names

This patch consolidates the different interface_pix_fmt, pixel_fmt, pix_fmt,
and pixfmt variables to a common name "bus_format" wherever they describe the
pixel format on the bus between display controller and encoder hardware.
At the same time, it renames imx_drm_panel_format to imx_drm_set_bus_format.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Tested-by: Emil Renner Berthing <kernel@esmil.dk>
diff --git a/drivers/gpu/drm/imx/dw_hdmi-imx.c b/drivers/gpu/drm/imx/dw_hdmi-imx.c
index 61ef987..1834ac8 100644
--- a/drivers/gpu/drm/imx/dw_hdmi-imx.c
+++ b/drivers/gpu/drm/imx/dw_hdmi-imx.c
@@ -123,7 +123,7 @@
 
 static void dw_hdmi_imx_encoder_prepare(struct drm_encoder *encoder)
 {
-	imx_drm_panel_format(encoder, MEDIA_BUS_FMT_RGB888_1X24);
+	imx_drm_set_bus_format(encoder, MEDIA_BUS_FMT_RGB888_1X24);
 }
 
 static struct drm_encoder_helper_funcs dw_hdmi_imx_encoder_helper_funcs = {