Add S2R functionality for HDMI and Mixer

Add S2R functionality for HDMI and Mixer

This patch adds clock gating support for HDMI and
Mixer via runtime PM routines.
Also the error handling in case if it fails to
configure gpio for external interrupt,is done.

	BUG=chrome-os-partner:12958
	    chrome-os-partner:14185
	Test=On Snow,
	DISPLAY=":0" xset dpms force off/on
	HDMI hotplug in and out
	rtcwake -m mem -s <X>
	This system behaves as expected.

Change-Id: I4d59c74a6f74ab375408198a8da7f124f9ae82f4
Signed-off-by: Shirish S <s.shirish@samsung.com>
Signed-off-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
Signed-off-by: Rahul Sharma <rahul.sharma@samsung.com>
Reviewed-on: https://gerrit.chromium.org/gerrit/33685
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Jon Kliegman <kliegs@chromium.org>
Tested-by: Jon Kliegman <kliegs@chromium.org>
Commit-Ready: Shirish S <shirish@chromium.org>