Just like MULTIPLY HALFWORD IMMEDIATE (MGHI), only the second operand
(signed 16 bit) comes from memory.

Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200928122717.30586-6-david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>