drm/bridge/sii8620: add remote control support

MHL specification defines Remote Control Protocol(RCP) to
send input events between MHL devices.
The driver now recognizes RCP messages and reacts to them
by reporting key events to input subsystem, allowing
a user to control a device using TV remote control.

Signed-off-by: Maciej Purski <m.purski@samsung.com>
Acked-by: Sean Young <sean@mess.org>
Acked-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1503565087-19730-1-git-send-email-m.purski@samsung.com

drivers/gpu/drm/bridge/Kconfig

@@ -71,7 +71,7 @@ config DRM_PARADE_PS8622
 
 config DRM_SIL_SII8620
 	tristate "Silicon Image SII8620 HDMI/MHL bridge"
-	depends on OF
+	depends on OF && RC_CORE
 	select DRM_KMS_HELPER
 	help
 	  Silicon Image SII8620 HDMI/MHL bridge chip driver.