If the whitelist already exists in the controller then the controller
should not add the device tot the whitelist and should return success.
In that case the counting of entries in the whitelist in the host will
be wrong.
Remove all whitelist counting in the host, and instead rely on the error
reported by the controller for this.
The controller should return error if the whitelist is full.
The controller should return error if use of whitelist was requested but
the whitelist was empty.
Signed-off-by: Joakim Andersson <joakim.andersson@nordicsemi.no>