The list of controllers can be counted ahead of time and inline
inside the AMP discover handling. There is no need to export such
a function at all.

In addition just count the AMP controller and only allocated space
for a single mandatory BR/EDR controller. No need to allocate more
space than needed.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>