ARM: dts: msm: Add batfet control regulator device

Add battery FET (batfet) regulator device that allows
consumers to control the batfet's HPM/LPM mode when the PMIC
goes to sleep.

CRs-Fixed: 503417
Change-Id: I69902be97af4c9d9c22a62594f9a33203691492e
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>