usb: dwc3: of-simple: fix use-after-free on remove

This is a direct consequence of not paying attention to the order of things. If driver were to assume that pm_domain->activate() would do the right thing for the device -- meaning that probe would run with an active device --, then we wouldn't need that pm_runtime_get() call on probe at all. Rather we would follow the sequence:

	pm_runtime_forbid()
	pm_runtime_set_active()
	pm_runtime_enable()

	/* do your probe routine */

	pm_runtime_put_noidle()

Then you remove you would need to call pm_runtime_get_noresume() to balance out the pm_runtime_put_noidle() there.

Anyway, with an assumption like this, after all platform_devices are converted over, the assumption can be moved into the bus code and, low and behold, to enable runtime pm for your driver, all you have to is implement your callbacks and add pm_runtime_put_noidle() to probe and pm_runtime_get_noresume() to remove (apart from, of course, making sure the device isn't allowed to runtime_suspend when it's actually busy).

Do you see the end goal?

(If you need to know why the pm_runtime_put_noidle(), remember that pm_runtime_set_active() increments the usage counter, so pm_runtime_put_noidle is basically allowing pm_runtime to happen as soon as userspace writes "auto" to /sys/..../power/control)