drm/vc4: dpi: Support RGB565 format

The RGB565 format with padding over 24 bits
(MEDIA_BUS_FMT_RGB565_1X24_CPADHI) is supported by the vc4 DPI
controller. This is what the Geekworm MZP280 DPI display uses, so let's
add support for it in the DPI controller driver.
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20221013-rpi-dpi-improvements-v3-4-eb76e26a772d@cerno.techSigned-off-by: Maxime Ripard <maxime@cerno.tech>

drivers/gpu/drm/vc4/vc4_dpi.c

@@ -182,6 +182,10 @@ static void vc4_dpi_encoder_enable(struct drm_encoder *encoder)
 				dpi_c |= VC4_SET_FIELD(DPI_FORMAT_16BIT_565_RGB_3,
 						       DPI_FORMAT);
 				break;
+			case MEDIA_BUS_FMT_RGB565_1X24_CPADHI:
+				dpi_c |= VC4_SET_FIELD(DPI_FORMAT_16BIT_565_RGB_2,
+						       DPI_FORMAT);
+				break;
 			default:
 				DRM_ERROR("Unknown media bus format %d\n",
 					  bus_format);