usb: dwc2: disable platform lowlevel hw resources during shutdown

usb: dwc2: disable platform lowlevel hw resources during shutdown

On some SoC platforms, in shutdown stage, most components' power is cut
off, but there's still power supply to the so called always-on
domain, so if the dwc2's regulator is from the always-on domain, we
need to explicitly disable it to save power.

Disable platform lowlevel hw resources such as phy, clock and
regulators etc. in device shutdown hook to reduce non-necessary power
consumption when the platform enters shutdown stage.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Acked-by: Minas Harutyunyan <hminas@synopsys.com>
Link: https://lore.kernel.org/r/20250629094655.747-1-jszhang@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>