FROMLIST: KVM: arm64: Restrict FF-A host version renegotiation

Prevent the host from re-negotiating a lesser minor version with the
hypervisor. Once the hypervisor negotiates a version, that should
remain locked in. Fix the current behaviour by returning NOT_SUPPORTED
to avoid the FF-A interoperability rules with lesser minor versions that
allow the host version to downgrade.

Bug: 269285339
Link: https://lore.kernel.org/all/20250516-virtio-msg-ffa-v4-1-580ee70e5081@google.com


Change-Id: I18e26a1a467f89ce421f31f577b3f15c37dfcf1a
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Per Larsen <perlarsen@google.com>