Bluetooth: Fix redundant encryption request for reauthentication

When we're performing reauthentication (in order to elevate the
security level from an unauthenticated key to an authenticated one) we
do not need to issue any encryption command once authentication
completes. Since the trigger for the encryption HCI command is the
ENCRYPT_PEND flag this flag should not be set in this scenario.
Instead, the REAUTH_PEND flag takes care of all necessary steps for
reauthentication.

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