drm/meson: Use optional canvas provider

This is the first step into converting the meson/drm driver to use
the canvas module.

If a canvas provider node is detected in DT, use it. Otherwise,
fall back to what is currently being done.

Signed-off-by: Maxime Jourdan <mjourdan@baylibre.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
[narmstrong: added back priv in meson_drv_unbind()]
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181105104508.23090-3-mjourdan@baylibre.com
diff --git a/drivers/gpu/drm/meson/Kconfig b/drivers/gpu/drm/meson/Kconfig
index 3ce51d8..c28b69f 100644
--- a/drivers/gpu/drm/meson/Kconfig
+++ b/drivers/gpu/drm/meson/Kconfig
@@ -7,6 +7,7 @@
 	select DRM_GEM_CMA_HELPER
 	select VIDEOMODE_HELPERS
 	select REGMAP_MMIO
+	select MESON_CANVAS
 
 config DRM_MESON_DW_HDMI
 	tristate "HDMI Synopsys Controller support for Amlogic Meson Display"