disp: msm: dp: add support for 7nm pll

Add support for 7nm pll. Only some offsets are different from 5nm
pll while the rest are same.

Change-Id: If61cd604d7f8221c659f1b83761647e86e3b6627
Signed-off-by: Rajat Gupta <rajatgu@codeaurora.org>