clk: qcom: gdsc-regulator: refactor gdsc_probe() to reduce complexity

Refactor the gdsc_probe() function to reduce its cyclomatic
complexity.  This helps to make the gdsc-regulator driver easier
to understand and maintain.

Change-Id: I285c01a6cca7609bb09ef0c769db5bde8dc142a6
Signed-off-by: David Collins <collinsd@codeaurora.org>