net: fec: Better handle pm_runtime_get() failing in .remove()

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

net: fec: Better handle pm_runtime_get() failing in .remove()

In the (unlikely) event that pm_runtime_get() (disguised as pm_runtime_resume_and_get()) fails, the remove callback returned an error early. The problem with this is that the driver core ignores the error value and continues removing the device. This results in a resource leak. Worse the devm allocated resources are freed and so if a callback of the driver is called later the register mapping is already gone which probably results in a crash.