clk: msm: clock-mmss-8996: Add dynamic_update support for MMPLL9

Add the dynamic_update flag and define the update_mask to enable
MMPLL9 to be able to dynamically update its frequency.

CRs-Fixed: 988270
Change-Id: I48a40f879b07469a954065d568c12e4a75925292
Signed-off-by: Devesh Jhunjhunwala <deveshj@codeaurora.org>