arm64: adi_bcm*_defconfig: Remove from branch

The defconfig is not related to this branch and cannot be updated to
be compatible with it since it requires drivers only present in the
rpi fork. Therefore, remove adi_bcm2711_defconfig, adi_bcm2712_defconfig
from this branch.

Signed-off-by: Jorge Marques <[email protected]>

Author: gastmaier