Bluetooth: mgmt: Fix clear_uuids response

Since the clear_uuids operation doesn't send an immediate HCI command
but just sets off a timer to wait for subsequent add_uuid calls it
doesn't make sense to wait until the timer fires off to send the
response. Instead send the response immediately.

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