mediatek: dts: fix the broken memory node

mediatek: dts: fix the broken memory node

Add the missing "device_type" property to fix the memory node. The
Linux kernel can not get the memory size without it. Though u-boot
can automatically fixup the memory node by adding the "device_type"
and "reg" properties if the CONFIG_ARCH_FIXUP_FDT_MEMORY symbol is
enabled, it's better not to rely on this optional feature. This
patch also adds the reg address for the memory node name to follow
the naming rules.

Signed-off-by: Shiji Yang <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/19741
Signed-off-by: Hauke Mehrtens <[email protected]>