Bluetooth: controller: Fix header inclusion

Use correct headers to make the inclusion of lll.h work when
CONFIG_BT_CTLR_USER_EXT is enabled.

Signed-off-by: Thomas Ebert Hansen <thoh@oticon.com>

subsys/bluetooth/controller/ll_sw/nordic/hal/nrf5/ticker.c

@@ -7,6 +7,7 @@
 
 #include <stdbool.h>
 #include <sys/dlist.h>
+#include <sys/util.h>
 
 #include "hal/cntr.h"
 

subsys/bluetooth/controller/ll_sw/ull_sched.c

@@ -4,11 +4,9 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-#include <stddef.h>
+#include <zephyr.h>
 
-#include <zephyr/types.h>
 #include <sys/byteorder.h>
-#include <toolchain.h>
 
 #include "hal/ccm.h"
 #include "hal/radio.h"