esp_dpp: Fix retry with esp_supp_dpp_start_listen after failure

This fixes a subtle bug in which ESP_ERR_DPP_TX_FAILURE errors would
call esp_supp_dpp_stop_listen which sets the s_dpp_stop_listening flag
to true.  Subsequent attempts to restart listening with
esp_supp_dpp_start_listen then only attempt to listen once more for
500ms before reading the s_dpp_stop_listening flag again and giving up.

This contributes greatly to #10615, but the fix here is still largely
a work-around as it sometimes requires manually retrying a couple times
before it works.  Without this fix, any number of retries by
deinit/init again will seemingly not work as the retries for currently
unknown reasons.

Signed-off-by: Shreyas Sheth <shreyas.sheth@espressif.com>

Closes #10865

components/wpa_supplicant/esp_supplicant/src/esp_dpp.c

@@ -586,6 +586,7 @@ esp_err_t esp_supp_dpp_start_listen(void)
         return ESP_ERR_INVALID_STATE;
     }
 
+    s_dpp_stop_listening = false;
     return esp_dpp_post_evt(SIG_DPP_LISTEN_NEXT_CHANNEL, 0);
 }