drm/meson: Add G12A support for plane handling in CRTC driver

This patch adds support for the new OSD+VD Plane blending module
in the CRTC code by adding the G12A code to manage the blending
module and setting the right OSD1 & VD1 plane registers.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Jerome Brunet <jbrunet@baylibre.com>
Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190325141824.21259-8-narmstrong@baylibre.com

drivers/gpu/drm/meson/meson_drv.h

@@ -62,6 +62,10 @@ struct meson_drm {
 		uint32_t osd_sc_h_phase_step;
 		uint32_t osd_sc_h_ctrl0;
 		uint32_t osd_sc_v_ctrl0;
+		uint32_t osd_blend_din0_scope_h;
+		uint32_t osd_blend_din0_scope_v;
+		uint32_t osb_blend0_size;
+		uint32_t osb_blend1_size;
 
 		bool vd1_enabled;
 		bool vd1_commit;