s390/qdio: move SSQD Sniffer mask definition

Put the Sniffer bit next to all the other CHSC AC2 bits.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>