drm/vc4: dpi: Fix format mapping for RGB565

The mapping is incorrect for RGB565_1X16 as it should be
DPI_FORMAT_18BIT_666_RGB_1 instead of DPI_FORMAT_18BIT_666_RGB_3.

Fixes: 08302c35 ("drm/vc4: Add DPI driver")
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20221013-rpi-dpi-improvements-v3-7-eb76e26a772d@cerno.techSigned-off-by: Maxime Ripard <maxime@cerno.tech>

drivers/gpu/drm/vc4/vc4_dpi.c

@@ -185,7 +185,7 @@ static void vc4_dpi_encoder_enable(struct drm_encoder *encoder)
 						       DPI_FORMAT);
 				break;
 			case MEDIA_BUS_FMT_RGB565_1X16:
-				dpi_c |= VC4_SET_FIELD(DPI_FORMAT_16BIT_565_RGB_3,
+				dpi_c |= VC4_SET_FIELD(DPI_FORMAT_16BIT_565_RGB_1,
 						       DPI_FORMAT);
 				break;
 			case MEDIA_BUS_FMT_RGB565_1X24_CPADHI: