Bluetooth: Fix mgmt handling of power on failures

If hci_dev_open fails we need to ensure that the corresponding
mgmt_set_powered command gets an appropriate response. This patch fixes
the missing response by adding a new mgmt_set_powered_failed function
that's used to indicate a power on failure to mgmt. Since a situation
with the device being rfkilled may require special handling in user
space the patch uses a new dedicated mgmt status code for this.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Cc: stable@vger.kernel.org
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: John W. Linville <linville@tuxdriver.com>