Bluetooth: Reintroduce socket restrictions for LE sockets

Right now we do not allow user space to use connection oriented channels
on LE, and the only CID that can be used is the Attribute Protocol one.
These restrictions went away together with the recent refactoring of the
L2CAP code, but this patch puts them back to their appropriate places.

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