msm: mdss: add dynamic fps support for hdmi

Add support for dynamic fps up to three decimal values for
hdmi. The new fps is provided in multiple of 1000. eg. for
60 fps, 60000 is provided and for 59.94fps, 59940 is provided.

Change-Id: Ib16bf546721ba204f8a47733327e7be77b76b821
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>