bmips: add experimental ethernet support

This adds experimental ethernet support for BCM6318, BCM6328, BCM6362, BCM6368
and BCM63268.
BCM6358 needs a different driver, so there's no support for now.

Working devices:
- Comtrend AR-5315u
- Comtrend AR-5387un
- Comtrend VR-3025u
- Comtrend VR-3032u

Not working devices:
- Netgear DGND3700 v2 (no idea on how the external switch is connected)
- Huawei HG556a ver B (BCM6358 needs a separate driveer)

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

target/linux/bmips/config-5.10

@@ -3,8 +3,15 @@ CONFIG_ARCH_HIBERNATION_POSSIBLE=y
 CONFIG_ARCH_MMAP_RND_BITS_MAX=15
 CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX=15
 CONFIG_ARCH_SUSPEND_POSSIBLE=y
+CONFIG_B53=y
+# CONFIG_B53_MDIO_DRIVER is not set
+CONFIG_B53_MMAP_DRIVER=y
+# CONFIG_B53_SERDES is not set
+CONFIG_B53_SPI_DRIVER=y
+# CONFIG_B53_SRAB_DRIVER is not set
 CONFIG_BCM6345_EXT_IRQ=y
 CONFIG_BCM6345_L1_IRQ=y
+CONFIG_BCM6368_ENETSW=y
 CONFIG_BCM63XX_POWER=y
 CONFIG_BCM7038_L1_IRQ=y
 CONFIG_BCM7038_WDT=y
@@ -103,6 +110,7 @@ CONFIG_GPIOLIB=y
 # CONFIG_GPIO_BRCMSTB is not set
 CONFIG_GPIO_GENERIC=y
 CONFIG_GPIO_GENERIC_PLATFORM=y
+CONFIG_GRO_CELLS=y
 CONFIG_HANDLE_DOMAIN_IRQ=y
 CONFIG_HARDIRQS_SW_RESEND=y
 CONFIG_HAS_DMA=y
@@ -128,6 +136,8 @@ CONFIG_LOCK_DEBUGGING_SUPPORT=y
 CONFIG_LZO_COMPRESS=y
 CONFIG_LZO_DECOMPRESS=y
 CONFIG_MDIO_BUS=y
+CONFIG_MDIO_BUS_MUX=y
+CONFIG_MDIO_BUS_MUX_BCM6368=y
 CONFIG_MDIO_DEVICE=y
 CONFIG_MEMFD_CREATE=y
 CONFIG_MFD_SYSCON=y
@@ -163,7 +173,14 @@ CONFIG_MTD_CFI_STAA=y
 CONFIG_MTD_JEDECPROBE=y
 # CONFIG_MTD_PARSER_IMAGETAG is not set
 CONFIG_NEED_DMA_MAP_STATE=y
+CONFIG_NET_DEVLINK=y
+CONFIG_NET_DSA=y
+CONFIG_NET_DSA_TAG_BRCM=y
+CONFIG_NET_DSA_TAG_BRCM_COMMON=y
+CONFIG_NET_DSA_TAG_BRCM_LEGACY=y
+CONFIG_NET_DSA_TAG_BRCM_PREPEND=y
 CONFIG_NET_FLOW_LIMIT=y
+CONFIG_NET_SWITCHDEV=y
 CONFIG_NO_EXCEPT_FILL=y
 CONFIG_NO_GENERIC_PCI_IOPORT_MAP=y
 CONFIG_NR_CPUS=2
@@ -181,6 +198,7 @@ CONFIG_PCI_DRIVERS_LEGACY=y
 CONFIG_PERF_USE_VMALLOC=y
 CONFIG_PGTABLE_LEVELS=2
 CONFIG_PHYLIB=y
+CONFIG_PHYLINK=y
 CONFIG_PHYSICAL_START=0x80010000
 CONFIG_PHY_BCM63XX_USBH=y
 # CONFIG_PHY_BRCM_SATA is not set