clk: qcom: Add common regulator handle initialization

To clean up clock controllers probe function, move to common regulator
handle initialization.

Also add common multiple regulator initialization support within
single clk_vdd_class.

Change-Id: I999966d3bc877e0e8bcbb54839c0dd86f41869bd
Signed-off-by: Vivek Aknurwar <viveka@codeaurora.org>