clk: qcom: clk-branch: Increase the polling timeout for branch clocks

In certain cases, branch clocks might take longer than the
current polling timeout of 200usecs to turn on/off. Increase
this value to 500usecs instead.

Change-Id: I731c442ca4e38545041d7afb0c07bcee67095530
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>