msm: krait-regulator: prepare for soft start workaround

The krait-regulator-pmic.h will expose an api to be called just
before the L2 is power collapsed. Move krait-regulator-pmic.h to
an appropriate location under include/soc/qcom/krait-regulator-pmic.h

Change-Id: I6fa6ce987a5490d727a3321c3d4e70ba7336489d
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>