apm821xx: DTB: fix warnings related to sata-port warnings

apm821xx: DTB: fix warnings related to sata-port warnings

This patch silences the following warnings:
>netgear-wndr4700.dts:168.3-13:Warning (reg_format): /plb/sata@bffd1800/sata-port@0:reg:property has invalid length (4 bytes) (#address-cells == 2, #size-cells == 1)
>netgear-wndr4700.dts:167.26-170.4: Warning (avoid_default_addr_size):/plb/sata@bffd1800/sata-port@0: Relying on default #address-cells value
>netgear-wndr4700.dts:167.26-170.4: Warning (avoid_default_addr_size):/plb/sata@bffd1800/sata-port@0: Relying on default #size-cells value

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>