msm: krait-regulator: Add flag to disable LDO mode usage

Add a feature which allows to disable using LDO. When enabled, the
core continues to run from BHS possibly seeing a higher input voltage.
This may increase the leakage from the core but will not cause a
brownout.

Change-Id: I793af7a9eeddfd52f5fea9b4c59c774f0272f431
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>