ARM: bcm: Removed forced select of interrupt controllers

Now that the various second level interrupt controllers have been moved
to IRQCHIP_PLATFORM_DRIVER and they do default to ARCH_BRCMSTB and
ARCH_BCM2835 where relevant, remove their forced selection from the
machine entry to allow an user to build them as modules.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211020184859.2705451-13-f.fainelli@gmail.com