struct initialization in old style, init in with 0 instead of NULL

src/hci_transport_h4_dma.c

@@ -103,7 +103,7 @@ static  void (*packet_handler)(uint8_t packet_type, uint8_t *packet, uint16_t si
 
 static data_source_t hci_transport_h4_dma_ds = {
   /*  .item    = */  NULL,
-  /*  .fd      = */  NULL,
+  /*  .fd      = */  0,
   /*  .process = */  h4_process
 };
 

src/hci_transport_h4_ehcill_dma.c

@@ -135,7 +135,7 @@ static uint8_t   tx_packet_type;
 // data source used in run_loop
 static data_source_t hci_transport_h4_dma_ds = {
   /*  .item    = */  NULL,
-  /*  .fd      = */  NULL,
+  /*  .fd      = */  0,
   /*  .process = */  h4_process
 };