clk: qcom: mdss: add support for dynamic refresh on DSI 14nm PLL

Add CLK_SET_RATE_NO_REPARENT flag for the software mux clocks in
DSI 14nm PLL driver which is needed for dynamic refresh feature.
Update the dynamic fps structure to align the PLL codes with
vco frequency instead of fps.

Change-Id: I533f615ce51be7229171b6accac3f14ab2dca949
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>