KVM: arm64: Handle FFA_FEATURES call from the host

Filter out advertising unsupported features, and only advertise
features and properties that are supported by the hypervisor proxy.

Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230523101828.7328-10-will@kernel.org


Signed-off-by: Oliver Upton <oliver.upton@linux.dev>