usb: dwc3-msm: Add regulators voting for SS and HS PHYs

DWC3 has two PHYs for both super-speed and high-speed
mode of operations. Add voting for the regulators which
are required by both the PHYs in the driver.

As of now, these regulators are turned ON when driver's
probe routine gets called and stays ON. Later as part of
low power mode support in the driver these regulators would
be selectively disabled depending on the PHY under use.

Change-Id: I218c5b06adf2d5af297cba2d64e9427be9bb48f8
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>