regulator: qcom-smd: Postpone voltage changes to enable

Move the voltage request for disabled regulators to the subsequent
enable request.

It's been observed that while booting the QCS404 EVB, the effort of
bringing PMS405 LDO3 into its configured voltage range causes the system
to lock up.

Enabling the regulator from the consumer drivers shortly after works
fine, which indicates that there would be an ordering constraint
involved, but the exact reason for the need of this is still uncertain.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>