Bluetooth: Remove L2CAP Extended Features from Kconfig

This reverts commit 84fb0a63

 which adds
the L2CAP Extended Features to the Kconfig, that is actually not needed.
One can use other mechanisms to enable L2CAP Extended Features.

Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>