hw/s390x: Fix bad mask in time2tod()

hw/s390x: Fix bad mask in time2tod()

Since "s390x/tcg: avoid overflows in time2tod/tod2time", the
time2tod() function tries to deal with the 9 uppermost bits in the
time value, but uses the wrong mask for this: 0xff80000000000000 should
be used instead of 0xff10000000000000 here.

Fixes: 14055ce53c2d901d826ffad7fb7d6bb8ab46bdfd
Cc: qemu-stable@nongnu.org
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1544792887-14575-1-git-send-email-thuth@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
[CH: tweaked commit message]
Signed-off-by: Cornelia Huck <cohuck@redhat.com>