Use 0000 as pin key for PORCHE_PAIRING_CONFLICT issue

For PORCHE_PAIRING_CONFLICT issue when there are no other paired devices
available in bluetooth list pairing always fails (as per implementation
in bluedroid stack).
In this case when pin key request is received use 0000 as the pin key
so that pairing is successful.

Bug 67614

Change-Id: I67b2e689cfcc52c93fdda62dd742812698baa0e6

stack/btm/btm_sec.c

@@ -4774,6 +4774,10 @@ void btm_sec_pin_code_request (UINT8 *p_bda)
     tBTM_SEC_DEV_REC *p_dev_rec;
     tBTM_CB          *p_cb = &btm_cb;
 
+#ifdef PORCHE_PAIRING_CONFLICT
+    UINT8 default_pin_code_len = 4;
+    PIN_CODE default_pin_code = {0x30, 0x30, 0x30, 0x30};
+#endif
     BTM_TRACE_EVENT3 ("btm_sec_pin_code_request()  State: %s, BDA:%04x%08x",
                       btm_pair_state_descr(btm_cb.pairing_state),
                       (p_bda[0]<<8)+p_bda[1], (p_bda[2]<<24)+(p_bda[3]<<16)+(p_bda[4]<<8)+p_bda[5] );
@@ -4807,7 +4811,8 @@ void btm_sec_pin_code_request (UINT8 *p_bda)
             BTM_TRACE_EVENT0 ("btm_sec_pin_code_request from remote dev. for local initiated pairing");
             if(! btm_cb.pin_code_len_saved)
             {
-                btsnd_hcic_pin_code_neg_reply (p_bda);
+                btm_sec_change_pairing_state (BTM_PAIR_STATE_WAIT_AUTH_COMPLETE);
+                btsnd_hcic_pin_code_req_reply (p_bda, default_pin_code_len, default_pin_code);
             }
             else
             {