arm64: insn: Add SVE instruction class

SVE has been public for some time now. Let the decoder acknowledge
its existence.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Link: https://lore.kernel.org/r/20210303170536.1838032-6-jthierry@redhat.com


Signed-off-by: Will Deacon <will@kernel.org>