usb: phy: msm-hsusb: Only turn on/off regulators if retentioned

The HSPHY should only turn off its regulators if it has entered
retention mode, which only should happen if not in host mode and
without a charger or cable connected. The resume path should
re-enable these regulators if they have been turned off, but
checking the host or charger connected states may be error-prone
since they could have been changed by the controller in between
suspend and resume. Instead keep track of this status in an
lpm_flags member in order to properly reverse the operations
when resuming the PHY.

Change-Id: If021654b0e34856e5ab8064129cf0d87aa017154
Signed-off-by: Jack Pham <jackp@codeaurora.org>