Bluetooth: Add full SMP BR/EDR support

When doing SMP over BR/EDR some of the routines can be shared with the
LE functionality whereas others needs to be split into their own BR/EDR
specific branches. This patch implements the split of BR/EDR specific
SMP code from the LE-only code, making sure SMP over BR/EDR works as
specified.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>