msm: mdss: add support for dynamic dsi phy timing calculation

The programming of the DSI Phy timing registers are dependent on
link frequency. In the current implementation, these values are
pre-computed statically based on the link rate required for a particular
panel. This approach does not scale very well, especially for use cases
when dynamically changing the refresh rate or resolution for a panel.
To address this, add support to dynamically compute the value for dsi
phy timing registers based on a particular link rate.

Change-Id: If1ff545318a540baee66f5357c519d7f428510c1
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>
Signed-off-by: Sandeep Panda <spanda@codeaurora.org>
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>
Signed-off-by: Ingrid Gallardo <ingridg@codeaurora.org>