arm64: dts: mediatek: mt7981b: add 'soc-uuid' cell to efuse

arm64: dts: mediatek: mt7981b: add 'soc-uuid' cell to efuse

The efuse of the MediaTek MT7981 contains a 16-byte unique identifier.
Add a 'soc-uuid' cell covering those 16 bytes to the nvmem defininition
of the efuse to allow easy access from userspace, eg. to generate a
persistent random MAC address on boards which don't have any
factory-assigned addresses.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>