MIPS: dts: Fix a typo in the node unit name

MIPS: dts: Fix a typo in the node unit name

The unit name was 8c00000 but since the reg property is declared as:

  reg = <0x0 0x4c00000 0x1 0xfb400000>;

the unit name should have been instead 4c00000.

Tested on MIPS Creator CI20 (v1):

$ cat /sys/firmware/devicetree/.../partitions/partition@4c00000/label;echo
system

Reported-by: James Hogan <jhogan@kernel.org>
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Cercueil <paul@crapouillou.net>
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/18529/
Signed-off-by: James Hogan <jhogan@kernel.org>