usb: dwc3: core: Prevent USB core invalid event buffer address access

In the Linux kernel, the following vulnerability has been resolved:

usb: dwc3: core: Prevent USB core invalid event buffer address access

This commit addresses an issue where the USB core could access an

invalid event buffer address during runtime suspend, potentially causing

SMMU faults and other memory issues in Exynos platforms. The problem

arises from the following sequence.

1. In dwc3_gadget_suspend, there is a chance of a timeout when

moving the USB core to the halt state after clearing the

run/stop bit by software.

2. In dwc3_core_exit, the event buffer is cleared regardless of

the USB core's status, which may lead to an SMMU faults and

other memory issues. if the USB core tries to access the event

buffer address.

To prevent this hardware quirk on Exynos platforms, this commit ensures

that the event buffer address is not cleared by software when the USB

core is active during runtime suspend by checking its status before

clearing the buffer address.