target/i386: Assert !SVME for user-only

target/i386: Assert !SVME for user-only

Most of the VMM instructions are already disabled for user-only,
by being usable only from ring 0.

The spec is intentionally loose for VMMCALL, allowing the VMM to
define syscalls for user-only.  However, we're not emulating any
VMM, so VMMCALL can just raise #UD unconditionally.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210514151342.384376-31-richard.henderson@linaro.org>