msm: mdss: add multi-mode support for dynamic fps

In some cases, updating fps need both porch and clock
update. Add support to update both porch and clock settings
for a given resolution to attain required fps.

Change-Id: I8c75ef09121c2d20e04380ead2b805c7b114acad
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>