ARM: dts: BCM5301X: remove unnecessary address & size cells from Asus RT-AC88U

Remove the unnecessary #address-cells & #size-cells in the gpio-keys node
from the device tree of Asus RT-AC88U.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>