SAP: Make it possible to enforce a 16-digit pin code (1/5)

This change enable the posibility to enforce using a
16-digit pin or MITM for a RFCOMM or L2CAP connection.

This is needed for the SIM access profile.

Change-Id: I02886ce284f27295205def3c66fb76372f5dab4f
Signed-off-by: Casper Bonde <c.bonde@samsung.com>