UVI-2021-1000237 mt76: mt7915: fix memleak when mt7915_unregister_device()

mt76: mt7915: fix memleak when mt7915unregisterdevice This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v5.12.4 by commit...