msm: mdss: add support to parse dynamic refresh rate range

DSI panel dynamic refresh rate range varies from panel to panel.
Add support to parse dynamic refresh range from the panel device
tree. If the range is not specified, use the default range from
30 to max panel supported rate.

Change-Id: Iac5adebe187bdc7abd4e82464de81305862df794
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>