target/s390x: convert to DisasJumpType

The only non-trivial modification is the use of DISAS_TOO_MANY
in the same way is used by the generic translation loop.

Acked-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Cornelia Huck <cohuck@redhat.com>
Cc: Alexander Graf <agraf@suse.de>
Cc: qemu-s390x@nongnu.org
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>