SAP: Make it possible to enforce a 16-digit pin code (3/5)

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: I42ada9b36d24d43697a2010eccbc0103f15af77d
Signed-off-by: Casper Bonde <c.bonde@samsung.com>