msm: camera: cpas: Avoid clk set when streamon client is zero

Currently GDSC regualtor is being turn on upon calling
caps_hw_start(), when streamon client is zero. Also, GDSC
regulator is being enable after axi_clk_set(), which is conflicting
with clk framework expectation. This change bypass set_src_clk_rate
for the very first client, as clk_rate set here will anyways be
overwritten with default value while power on. This makes sure not
to call clk_set_rate() before GDSC regulator is turn on.

Change-Id: Ibbaa600244bc1623fd7aed33537f103b786d2169
Signed-off-by: Jigarkumar Zala <jzala@codeaurora.org>