Bluetooth: Remove broken force_lesc_support debugfs option

The force_lesc_support debugfs option never really worked. It has a race
condition between creating the debugfs entry and registering the L2CAP
fixed channel for BR/EDR SMP support.

Also this has been replaced with a working force_bredr_smp debugfs
switch that developers can use now.

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