s390/ap: exploit new B bit from QCI config info

This patch introduces an update to the ap_config_info
struct which is filled with the QCI subfunction. There
is a new bit apsb (short 'B') showing if the AP secure
bind facility is available. The patch also includes a
simple function ap_sb_available() wrapping this bit test.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>