arm64: make ARCH_BCM4908 select ARCH_BCMBCA

arm64: make ARCH_BCM4908 select ARCH_BCMBCA

BCA is a big set / family of devices sharing multiple hardware blocks.
It covers BCM4908, BCM63xx, BCM68xx devices and more.

Most of drivers that depend on ARCH_BCM4908 should actually depend on
ARCH_BCMBCA. To make such transition easier, cleaner and breakage-free
add a proper "select".

Later on - if we decide to keep ARCH_BCM4908 - it may be moved under
ARCH_BCMBCA menu. Keeping it may be helpful for limited compiling of DTS
files and "default" Kconfig entires. Or we may just decide to drop it.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: William Zhang <william.zhang@broadcom.com>
Acked-by: Kursad Oney <kursad.oney@broadcom.com>
Link: https://lore.kernel.org/r/20220714045858.7786-1-zajec5@gmail.com
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>