msm: mdss: hdmi: add support to dynamically add new resolutions

Add sysfs node to allow adding new resolution to the resolutions
database and let the system configure to that resolution.

Change-Id: I881be3cf9a441502e25c7501ea5d5cf456f2f58e
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>