clk: qcom: mdss: update mdss-dsi-28lpm clk names

Update byte and pxl clk names in mdss-dsi-pll-28lpm to
match with those defined in gcc-sdm429w. Update the
compatibility string for mdss-dsi-pll-28lpm.

Change-Id: I74675ebee5674b1b0512dddcbc548cee224c7800
Signed-off-by: Nirmal Abraham <nabrah@codeaurora.org>