KVM: ia64: remove

KVM for ia64 has been marked as broken not just once, but twice even,
and the last patch from the maintainer is now roughly 5 years old.
Time for it to rest in peace.

Acked-by: Gleb Natapov <gleb@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>