Bluetooth: Remove L2CAP Extended Features from Kconfig

This reverts commit 84fb0a6334af0ccad3544f6972c055d90fbb9fbe 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>