ipq40xx: fix MAC address on Meraki MR33 and MR74 after nvmem-layout

...conversion.
Commit 2073601 ("kernel: backport nvmem v6.6 fixes and v6.7 changes")
has cauedthe device to no longer correctly read MAC address from its
onboard 24c64 EEPROM, because "at24" driver doesn't support legacy
nvmem-cell bindings [1] - and there was an explicit config option added
to mandate that behaviour in the following patch:

820-v6.7-0002-nvmem-add-explicit-config-option-to-read-old-syntax-.patch

But some of the devices, MR33 and MR74 included, weren't converted with
that as well.
Convert the definition to use proper fixed-layout binding to fix it.

The offending change was introduced between v23.05.0 and v23.05.1, and
found by bisection:
git bisect start
# status: waiting for both good and bad commits
# good: [bd4f415] OpenWrt v23.05.0: adjust config defaults
git bisect good bd4f415
# status: waiting for bad commit, 1 good commit known
# bad: [a58a866] OpenWrt v23.05.1: adjust config defaults
git bisect bad a58a866
# good: [3d0a78a] qualcommax: only build initramfs if CONFIG_TARGET_ROOTFS_INITRAMFS is set
git bisect good 3d0a78a
# bad: [21e5db9] build: add CycloneDX SBOM JSON support
git bisect bad 21e5db9
# good: [89184b1] mediatek: add build for MT7981 RFB
git bisect good 89184b1
# bad: [41f27bb] bcm53xx: add the latest fix version of brcm_nvram
git bisect bad 41f27bb
# good: [b649b0b] kernel: nvmem: fix "fixed-layout" & support "mac-base"
git bisect good b649b0b
# bad: [2073601] kernel: backport nvmem v6.6 fixes and v6.7 changes
git bisect bad 2073601
# good: [0669716] kernel: backport v6.6 nvmem changes
git bisect good 0669716
# first bad commit: [2073601] kernel: backport nvmem v6.6 fixes and v6.7 changes

Link: [1] openwrt#15393 (comment)
Fixes: 2073601 ("kernel: backport nvmem v6.6 fixes and v6.7 changes")
Fixes: openwrt#15393
Signed-off-by: Lech Perczak <lech.perczak@gmail.com>

target/linux/ipq40xx/files-6.6/arch/arm/boot/dts/qcom/qcom-ipq4029-insect-common.dtsi

@@ -128,13 +128,17 @@
 		pagesize = <32>;
 		reg = <0x50>;
 		read-only; /* This holds our MAC & Meraki board-data */
-		#address-cells = <1>;
-		#size-cells = <1>;
 
-		mac_address: mac-address@66 {
-			compatible = "mac-base";
-			reg = <0x66 0x6>;
-			#nvmem-cell-cells = <1>;
+		nvmem-layout {
+			compatible = "fixed-layout";
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			mac_address: mac-address@66 {
+				compatible = "mac-base";
+				reg = <0x66 0x6>;
+				#nvmem-cell-cells = <1>;
+			};
 		};
 	};
 };