clk: msm: gcc: add support for MDSS clocks for SDM439

Add a new compatible flag for sdm439/sdm429 for support of
MDSS clocks required for the functionality of MDSSS DSI PLL
and MDP/rotator vote clocks.

Change-Id: Ib32c901983687e33894a78da9da0dde479582f1d
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>