As we are moving between address spaces, we can use access_memmove()
without checking for destructive overlaps (especially of real storage
locations):
    "Each storage operand is processed left to right. The
    storage-operand-consistency rules are the same as
    for MOVE (MVC), except that when the operands
    overlap in real storage, the use of the common real-
    storage locations is not necessarily recognized."

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: David Hildenbrand <david@redhat.com>