mpc85xx: Fix HiveAP-330 nvmem mac loader

We actually need to enclose the whole section of partitions in a
`partitions { ... }` to assign it a `compatible = "fixed-partitions";
otherwise the partition referred to by `hwinfo` won't be registered
when bringing up MTD partitions, for example as per:

- <https://forum.openwrt.org/t/tp-link-c2600-missing-default-mac-mtd-partition-in-snapshot/103945/6>

- commit e2b03c16eb ("ipq806x: add missing enclosing partitions block for TP-Link C2600")'

Fixes: 8ec21d6bb2 ("mpc85xx: convert mtd-mac-address to nvmem implementation")
Signed-off-by: Martin Kennedy <hurricos@gmail.com>
[minor beautification]
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>

target/linux/mpc85xx/files/arch/powerpc/boot/dts/hiveap-330.dts

@@ -42,6 +42,11 @@
 			bank-width = <2>;
 			device-width = <1>;
 
+			partitions {
+				compatible = "fixed-partitions";
+				#address-cells = <1>;
+				#size-cells = <1>;
+
 				partition@0 {
 					reg = <0x0 0x40000>;
 					label = "dtb";
@@ -103,6 +108,7 @@
 				};
 			};
 		};
+	};
 
 	board_soc: soc: soc@ffe00000 {
 		ranges = <0x0 0x0 0xffe00000 0x100000>;