usb: phy: snps: Ensure VDDA regulator is put in HPM

To properly ensure that the vdd regulator is put in the correct
operating mode, it needs to have a call to regulator_set_load()
prior to being enabled. This is crucial for platforms where the
HS PHY is the only consumer of the regulator as it could be
inadvertently left in LPM mode and cause the PHY to not function
properly.

Change-Id: I87815c60f044d854ecc75ac6039fd80c2d3197aa
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>