Mark secure link as authenticated for LE

Without this change, reading an authenticated GATT characteristic using
BR/EDR  would fail with an insufficient authentication error.

Change-Id: I02f44cdf90635b470b21e8aad8240993cb0e8e42
diff --git a/stack/btm/btm_dev.c b/stack/btm/btm_dev.c
index 0189bda..46a15d0 100644
--- a/stack/btm/btm_dev.c
+++ b/stack/btm/btm_dev.c
@@ -152,9 +152,9 @@
         if (pin_length >= 16 ||
             key_type == BTM_LKEY_TYPE_AUTH_COMB ||
             key_type == BTM_LKEY_TYPE_AUTH_COMB_P_256) {
-            // Set the fiag if the link key was made by using either a 16 digit
+            // Set the flag if the link key was made by using either a 16 digit
             // pin or MITM.
-            p_dev_rec->sec_flags |= BTM_SEC_16_DIGIT_PIN_AUTHED;
+            p_dev_rec->sec_flags |= BTM_SEC_16_DIGIT_PIN_AUTHED | BTM_SEC_LINK_KEY_AUTHED;
         }
     }