clk: qcom: mdss: DSI clk changes for sdm660

The DSI-1 PLL byte and pclk names are updated
to make it similar to DSI-0 PLL clk names. Added
'xo_board' as the DSI VCO clk parent name for
for SDM660 and other legacy FB targets. Updated
the pll_revision and the gdsc status read api
to be compatible with SDM660.

Change-Id: I5b78bec899871cbd46ad48186edf9fc198a47b7e
Signed-off-by: Nirmal Abraham <nabrah@codeaurora.org>