iommu/apple-dart: Drop default ARCH_APPLE in Kconfig

iommu/apple-dart: Drop default ARCH_APPLE in Kconfig

When the first driver for Apple Silicon was upstreamed we accidentally
included `default ARCH_APPLE` in its Kconfig which then spread to almost
every subsequent driver. As soon as ARCH_APPLE is set to y this will
pull in many drivers as built-ins which is not what we want.
Thus, drop `default ARCH_APPLE` from Kconfig.

Signed-off-by: Sven Peter <sven@kernel.org>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Janne Grunau <j@jannau.net>
Link: https://lore.kernel.org/r/20250612-apple-kconfig-defconfig-v1-7-0e6f9cb512c1@kernel.org
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>