drm/meson: imply dw-hdmi i2s audio for meson hdmi

Imply the i2s part of the Synopsys HDMI driver for Amlogic SoCs.
This will enable the i2s part by default when meson hdmi driver
is enable but let platforms not supported by the audio subsystem
disable it if necessary.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190429102325.29022-1-jbrunet@baylibre.com

drivers/gpu/drm/meson/Kconfig

@@ -14,3 +14,4 @@ config DRM_MESON_DW_HDMI
 	depends on DRM_MESON
 	default y if DRM_MESON
 	select DRM_DW_HDMI
+	imply DRM_DW_HDMI_I2S_AUDIO