usb: dwc2: fix hang during shutdown if set as peripheral

dwc2 on most platforms needs phy controller, clock and power supply.
All of them must be enabled/activated to properly operate. If dwc2
is configured as peripheral mode, then all the above three hardware
resources are disabled at the end of the probe:

/* Gadget code manages lowlevel hw on its own */
if (hsotg->dr_mode == USB_DR_MODE_PERIPHERAL)
dwc2_lowlevel_hw_disable(hsotg);

But dwc2_driver_shutdown() tries to disable the interrupts on HW IP
level. This would result in hang during shutdown if dwc2 is configured
as peripheral mode.

Fix this hang by only disable and sync irq when lowlevel hw is enabled.

Fixes: 4fdf228cdf69 ("usb: dwc2: Fix shutdown callback in platform")
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://patch.msgid.link/20251104002503.17158-2-jszhang@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>