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: I5bf70d7aacc4c1fdc7a20a9458b7ce419fc66265
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>