msm: krait-regulator: Don't assume one core per phase

The current driver assumes that a phase can support one core running at
maximum frequency. It uses this assumption to cap the number of phases
it calculates.

This assumption may not be applicable for certain platforms which have
stronger bucks capable of supplying more current per phase. Use a
property to track how many cores can one phase support and use it
in the code to cap the number of phases.

Change-Id: I8482255f23c81c726816901a02e57e149aa8598d
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>