clk: qcom: videocc-sm8150: Update the RCG configuration for iris_clk_src

Update the frequency table for the video_cc_iris_clk_src
RCG to use a uniform RCG pre-divider of 2 for all supported
frequencies.

Change-Id: Ie22bbcd74a34ae9ec384bd053d6c3eae253f8a7e
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>