ramips: dts: explicitly set the partition reg size for Ruijie RG-EW1200G

ramips: dts: explicitly set the partition reg size for Ruijie RG-EW1200G

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

../dts/mt7621_ruijie_rg-ew1200g-pro-v1.1.dts:60.5-30: Warning (reg_format): /palmbus@1e000000/spi@b00/flash@0/partitions/partition@0:reg: property has invalid length (8 bytes) (#address-cells == 2, #size-cells == 1)
../dts/mt7621_ruijie_rg-ew1200g-pro-v1.1.dts:66.5-29: Warning (reg_format): /palmbus@1e000000/spi@b00/flash@0/partitions/partition@50000:reg: property has invalid length (8 bytes) (#address-cells == 2, #size-cells == 1)
../dts/mt7621_ruijie_rg-ew1200g-pro-v1.1.dts:72.5-29: Warning (reg_format): /palmbus@1e000000/spi@b00/flash@0/partitions/partition@60000:reg: property has invalid length (8 bytes) (#address-cells == 2, #size-cells == 1)
../dts/mt7621_ruijie_rg-ew1200g-pro-v1.1.dts:88.5-29: Warning (reg_format): /palmbus@1e000000/spi@b00/flash@0/partitions/partition@70000:reg: property has invalid length (8 bytes) (#address-cells == 2, #size-cells == 1)
../dts/mt7621_ruijie_rg-ew1200g-pro-v1.1.dts:94.5-29: Warning (reg_format): /palmbus@1e000000/spi@b00/flash@0/partitions/partition@80000:reg: property has invalid length (8 bytes) (#address-cells == 2, #size-cells == 1)
../dts/mt7621_ruijie_rg-ew1200g-pro-v1.1.dts:101.5-30: Warning (reg_format): /palmbus@1e000000/spi@b00/flash@0/partitions/partition@90000:reg: property has invalid length (8 bytes) (#address-cells == 2, #size-cells == 1)

Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
Link: https://github.com/openwrt/openwrt/pull/18242
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>