mips: dts: loongson: fix DTC unit name warnings

Fixes the following W=1 kernel build warning(s):
arch/mips/boot/dts/loongson/loongson64g-package.dtsi:42.30-49.5: Warning (simple_bus_reg): /bus@1fe00000/serial@1fe001e0: simple-bus unit address format error, expected "1fe00100"
arch/mips/boot/dts/loongson/loongson64g-package.dtsi:51.30-59.5: Warning (simple_bus_reg): /bus@1fe00000/serial@1fe001e8: simple-bus unit address format error, expected "1fe00110"

Signed-off-by: zhaoxiao <zhaoxiao@uniontech.com>
Acked-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>