usb: dwc3-msm: Set PHY_HOST_MODE flags when entering host mode

commit d84aa6ac ("usb: dwc3-msm: Remove POWER_SUPPLY_PROP_SCOPE
from USB") had inadvertently removed setting of the PHY_HOST_MODE
flags for the HS and SS PHYs when entering host mode, and clearing
them upon exiting. Add them back, as the PHYs may need to handle
low power mode settings differently versus peripheral mode.

Change-Id: Ia39f95bfaf2155a19b1cb33bd58667566959bf13
Signed-off-by: Jack Pham <jackp@codeaurora.org>