msm: krait-regulator: enable phase management based on cpu status

The current code enables phase management at late init stage. This is
safe except if the acpuclock driver moves to late init stage, we might end
up enabling phase management before the acpuclock driver gets to call
voltage and mode callbacks on already onlined cpus. We risk
prematurely lowering the phase count and browning out the device.
Instead check how many cpus are actually online at probe time and enable
phase management only after voltage and mode callbacks happen for them.

Change-Id: Ia63ec06a0793d5e33b28c89c872f1b822567f521
Signed-off-by: Patrick Cain <pcain@codeaurora.org>