Bluetooth: Force the process of unpair command if disconnect failed

The unpair process tries to disconnect any connection pending with
remote. If there are some connection in connecting state, disconnect
command will fail and unpair mgmt command will stay pending.

That pending mgmt command can cause strange behavior like automatic
unpair after a lost connection.

Signed-off-by: Jefferson Delfes <jefferson.delfes@openbossa.org>
Acked-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>