CVE-2026-98565: net: dsa: mt7530: fix NULL dereference on unbind of MT7531 and MT7621

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

net: dsa: mt7530: fix NULL dereference on unbind of MT7531 and MT7621

The core and io supplies are only requested for IDMT7530: both the devmregulatorget() in probe and the regulatorenable() in mt7530setup() are guarded by the switch id, but mt7530remove() disables them unconditionally. On an MT7621 or an MT7531 both pointers are still NULL from devmkzalloc(), so rmmod or a sysfs unbind calls regulatordisable() on NULL.