clk: msm: clock-mmss-8996: disable cache based clk rate

Use flag CLKFLAG_NO_RATE_CACHE for RCG and branch clock
for mdss_extpclk_clk used for HDMI interface. Using this
flag will allow the clock framework to calculate rate
again and not depend on the cached rates.

Change-Id: I88f8924074a23e5a6fd48ce6243c7db89580109b
Signed-off-by: Rahul Sharma <rahsha@codeaurora.org>