mt76: mt7615: fix rdd mcu cmd endianness

Similar to mt7915 driver, fix mt7615 radar mcu command endianness

Fixes: 2ce73efe ("mt76: mt7615: initialize radar specs from host driver")
Fixes: 70911d96

 ("mt76: mt7615: add radar pattern test knob to debugfs")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>