arm64: rsi: Add automatic arm-cca-guest module loading

arm64: rsi: Add automatic arm-cca-guest module loading

The TSM module provides guest identification and attestation when a
guest runs in CCA realm mode. By creating a dummy platform device,
let's ensure the module is automatically loaded. The udev daemon loads
the TSM module after it receives a device addition event. Once that
happens, it can be used earlier in the boot process to decrypt the
rootfs.

Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/20241220181236.172060-2-jeremy.linton@arm.com
Signed-off-by: Will Deacon <will@kernel.org>