USB: OTG: msm: Turn off the power rails for 8960 while going to LPM

Analog power rails(3.3V and 1.8V) can be turned off completly, if
there is no lekage currents while turning off the regulators.
Hence turn off the analog regulators completly when there is no
USB session active for 8960.

Change-Id: Iff9b3902cc711e463f740f608c009bc70a6848a2
Signed-off-by: Anji jonnala <anjir@codeaurora.org>