Do not mask out secure connections (SC) bit for BT <4.2

Bug: 25467621
Change-Id: Ifdb52295fa5b8c5a39524a722dc044227c735240
diff --git a/stack/smp/smp_act.c b/stack/smp/smp_act.c
index 0196261..2423cad 100644
--- a/stack/smp/smp_act.c
+++ b/stack/smp/smp_act.c
@@ -190,7 +190,6 @@
                             (const bt_bdaddr_t *)&p_cb->pairing_bda))
                     {
                         p_cb->loc_auth_req &= ~SMP_KP_SUPPORT_BIT;
-                        p_cb->loc_auth_req &= ~SMP_SC_SUPPORT_BIT;
                         p_cb->local_i_key &= ~SMP_SEC_KEY_TYPE_LK;
                         p_cb->local_r_key &= ~SMP_SEC_KEY_TYPE_LK;
                     }