Bluetooth: Use const for struct l2cap_ops field

The struct l2cap_ops field should not allow any modifications and thus
it is better declared as const.

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

diff --cc include/net/bluetooth/l2cap.h
Simple merge

diff --cc net/bluetooth/a2mp.c
Simple merge

diff --cc net/bluetooth/l2cap_sock.c
Simple merge