usb: dwc3-exynos: Make provision for vdd regulators

From: Vivek Gautam <gautam.vivek@samsung.com>

Facilitate getting required 3.3V and 1.0V VDD supply for
DWC3 controller on Exynos.

certain perripherals will now need to ensure that,
they request VDD regulators in their drivers, and enable
them so as to make them working.

Change-Id: Ice38f24d7454110b089366fe1183cd3d36ad50bc
Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
Cc: Anton Tikhomirov <av.tikhomirov@samsung.com>
(cherry picked from commit a719a6f96a03f9918bf644b94d2be490a1137705)