wifi: mt76: mt7915: expose device tree match table

On MT7986 the WiFi driver currently does not get automatically loaded,
requiring manual modprobing because the device tree compatibles are not
exported into metadata.

Add the missing MODULE_DEVICE_TABLE macro to fix this.

Fixes: 99ad32a4

 ("mt76: mt7915: add support for MT7986")
Signed-off-by: Lorenz Brun <lorenz@brun.one>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>