s390x/ioinst: Fixed alignment check in SCHM instruction

Register 2 only has to be aligned to a 32-byte boundary, not a
full page boundary.

Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
