mediatek: filogic: fix memory node invalid length dtc warnings

mediatek: filogic: fix memory node invalid length dtc warnings

Correct the dts memory reg property to fix the following dtc
warnings:

../dts/mt7986a-zyxel-ex5601-t0-stock.dts:19.3-33: Warning (reg_format): /memory@40000000:reg: property has invalid length (8 bytes) (#address-cells == 2, #size-cells == 2)
../dts/mt7986a-zyxel-ex5601-t0-ubootmod.dts:19.3-33: Warning (reg_format): /memory@40000000:reg: property has invalid length (8 bytes) (#address-cells == 2, #size-cells == 2)

Signed-off-by: Shiji Yang <yangshiji66@outlook.com>