dt-bindings: arm64: bcmbca: Merge BCM4908 into BCMBCA

dt-bindings: arm64: bcmbca: Merge BCM4908 into BCMBCA

BCM4908 is one of the Broadcom Broadband origin WLAN Router/Access
Pointer SoCs. It was originally added by Rafał before Broadcom
started to upstream the support for broadband SoCs. Now that Broadcom
Broadband SoC is supported under arch ARCH_BCMBCA, this patch moves
BCM4908 SoC device tree descriptions into BCMBCA binding.

Signed-off-by: William Zhang <william.zhang@broadcom.com>
Acked-by: Rafał Miłecki <rafal@milecki.pl>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220803175455.47638-2-william.zhang@broadcom.com
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>