kirkwood: dts: explicitly set the partition reg size for Blackarmor NAS220

kirkwood: dts: explicitly set the partition reg size for Blackarmor NAS220

Correct the mtd partition reg property size to address the following
dtc warnings:

kirkwood-blackarmor-nas220.dts:185.4-24: Warning (reg_format): /mbus@f1000000/nand@12f/partitions/partition@0:reg: property has invalid length (8 bytes) (#address-cells == 2, #size-cells == 1)
kirkwood-blackarmor-nas220.dts:191.4-28: Warning (reg_format): /mbus@f1000000/nand@12f/partitions/partition@a0000:reg: property has invalid length (8 bytes) (#address-cells == 2, #size-cells == 1)
kirkwood-blackarmor-nas220.dts:197.4-28: Warning (reg_format): /mbus@f1000000/nand@12f/partitions/partition@b0000:reg: property has invalid length (8 bytes) (#address-cells == 2, #size-cells == 1)
kirkwood-blackarmor-nas220.dts:203.4-30: Warning (reg_format): /mbus@f1000000/nand@12f/partitions/partition@c0000:reg: property has invalid length (8 bytes) (#address-cells == 2, #size-cells == 1)

Signed-off-by: Shiji Yang <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/18242
Signed-off-by: Hauke Mehrtens <[email protected]>