bcm4908: fix Asus GT-AX6000 image

1. Include Linux DTB
2. Add 50991 variant (seems to differ by 1 PHY we don't support yet)

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

target/linux/bcm4908/config-5.10

@@ -1,5 +1,6 @@
 CONFIG_64BIT=y
 CONFIG_ARCH_BCM4908=y
+CONFIG_ARCH_BCMBCA=y
 CONFIG_ARCH_DMA_ADDR_T_64BIT=y
 CONFIG_ARCH_KEEP_MEMBLOCK=y
 CONFIG_ARCH_MMAP_RND_BITS=18

target/linux/bcm4908/image/bootfs-bcm4912.its

@@ -12,9 +12,22 @@
 			data = /incbin/("${images_dir}/u-boot/u-boot-bcm4912.dtb");
 		};
 
-		fdt_GTAX6000 {
+		fdt_uboot_GTAX6000 {
 			description = "dtb";
 			data = /incbin/("${images_dir}/u-boot/GTAX6000.dtb");
+			arch = "arm64";
+			type = "flat_dt";
+			compression = "none";
+
+			hash-1 {
+				algo = "sha256";
+			};
+		};
+
+		fdt_linux_GTAX6000 {
+			description = "dtb";
+			data = /incbin/("${dts_dir}/broadcom/bcmbca/bcm4912-asus-gt-ax6000.dtb");
+			arch = "arm64";
 			type = "flat_dt";
 			compression = "none";
 
@@ -27,8 +40,26 @@
 	configurations {
 		conf_ub_GTAX6000 {
 			description = "GTAX6000";
-			fdt = "fdt_GTAX6000";
+			fdt = "fdt_uboot_GTAX6000";
 			loadables = "atf", "uboot";
 		};
+
+		conf_lx_GTAX6000 {
+			description = "BRCM 63xxx linux";
+			kernel = "kernel";
+			fdt = "fdt_linux_GTAX6000";
+		};
+
+		conf_ub_GTAX6000_50991 {
+			description = "GTAX6000_50991";
+			fdt = "fdt_uboot_GTAX6000";
+			loadables = "atf", "uboot";
+		};
+
+		conf_lx_GTAX6000_50991 {
+			description = "BRCM 63xxx linux";
+			kernel = "kernel";
+			fdt = "fdt_linux_GTAX6000";
+		};
 	};
 };

target/linux/bcm4908/patches-5.10/037-v5.20-0011-arm64-bcmbca-add-arch-bcmbca-machine-entry.patch

@@ -0,0 +1,31 @@
+From fdcd652ce2b6b819f5c4dc3cead5215c84ee6933 Mon Sep 17 00:00:00 2001
+From: William Zhang <william.zhang@broadcom.com>
+Date: Wed, 1 Jun 2022 15:56:50 -0700
+Subject: [PATCH] arm64: bcmbca: add arch bcmbca machine entry
+
+Add ARCH_BCMBCA config for Broadcom Broadband SoC chipsets
+
+Signed-off-by: William Zhang <william.zhang@broadcom.com>
+Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
+---
+ arch/arm64/Kconfig.platforms | 9 +++++++++
+ 1 file changed, 9 insertions(+)
+
+--- a/arch/arm64/Kconfig.platforms
++++ b/arch/arm64/Kconfig.platforms
+@@ -59,6 +59,15 @@ config ARCH_BCM_IPROC
+ 	help
+ 	  This enables support for Broadcom iProc based SoCs
+ 
++config ARCH_BCMBCA
++	bool "Broadcom Broadband SoC"
++	help
++	  Say Y if you intend to run the kernel on a Broadcom Broadband ARM-based
++	  BCA chipset.
++
++	  This enables support for Broadcom BCA ARM-based broadband chipsets,
++	  including the DSL, PON and Wireless family of chips.
++
+ config ARCH_BERLIN
+ 	bool "Marvell Berlin SoC Family"
+ 	select DW_APB_ICTL