clk: msm: mdss: update the frame rate count supported for DFPS

Update the number of frame rates supported for dynamic refresh
feature from 10 to 20. This is needed to support all the fps
values requested by display HAL between minimum fps and maxiumum
fps based on the requirement.

Change-Id: Ib7487ad17261ac8c4d6929787899161061e71078
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>