samples: wifi_provisioning_over_ble: Zero-init cnx_params to fix reconnect

Initialize wifi_connect_req_params to zero to avoid undefined values in
struct fields that caused reconnection to fail. This makes repeated
connects stable.

Signed-off-by: Tejus R S <ters@silabs.com>

Author: silabs-tejus

samples/wifi_provisioning_over_ble/src/main.c

@@ -174,6 +174,7 @@ void do_wifi_connect(void)
 		printk("\r\nmalloc failed\r\n");
 		return;
 	}
+	memset(cnx_params, 0, sizeof(struct wifi_connect_req_params));
 	context.connecting = true;
 	cnx_params->channel = WIFI_CHANNEL_ANY;
 	cnx_params->band = 0;