clk: qcom: mdss: add Display-port pll clock driver support

Add support for new Display-port PLL clock driver to handle
different DP panel resolutions in msm8998. Add separate files
to support this new PHY PLL block.

CRs-Fixed: 1009740
Change-Id: Ic282c7e14fc6e23f4d044cb6a58249bdb4c8c2d8
Signed-off-by: Chandan Uddaraju <chandanu@codeaurora.org>
Signed-off-by: Narendra Muppalla <narendram@codeaurora.org>