sdh: do not declare the event handlers in obsevers' macro

Do not declare the event handlers in the observers' macro.
Let the user decide the linkage of the handlers.

Signed-off-by: Emanuele Di Santo <emdi@nordicsemi.no>

Author: lemrey

doc/nrf-bm/release_notes/release_notes_changelog.rst

@@ -32,7 +32,7 @@ No changes since the latest nRF Connect SDK Bare Metal release.
 SoftDevice Handler
 ==================
 
-No changes since the latest nRF Connect SDK Bare Metal release.
+* Updated the :c:macro:`NRF_SDH_STATE_EVT_OBSERVER` and :c:macro:`NRF_SDH_STACK_EVT_OBSERVER` macros to not declare the handler prototype.
 
 Boards
 ======

include/bm/softdevice_handler/nrf_sdh.h

@@ -149,7 +149,6 @@ struct nrf_sdh_state_evt_observer {
  */
 #define NRF_SDH_STATE_EVT_OBSERVER(_observer, _handler, _ctx, _prio)                               \
 	PRIO_LEVEL_IS_VALID(_prio);                                                                \
-	static int _handler(enum nrf_sdh_state_evt, void *);                                       \
 	static TYPE_SECTION_ITERABLE(struct nrf_sdh_state_evt_observer, _observer,                 \
 				     nrf_sdh_state_evt_observers, PRIO_LEVEL_ORD(_prio)) = {       \
 		.handler = _handler,                                                               \
@@ -190,7 +189,6 @@ struct nrf_sdh_stack_evt_observer {
  */
 #define NRF_SDH_STACK_EVT_OBSERVER(_observer, _handler, _ctx, _prio)                               \
 	PRIO_LEVEL_IS_VALID(_prio);                                                                \
-	static void _handler(void *);                                                              \
 	static const TYPE_SECTION_ITERABLE(struct nrf_sdh_stack_evt_observer, _observer,           \
 					   nrf_sdh_stack_evt_observers, PRIO_LEVEL_ORD(_prio)) = { \
 		.handler = _handler,                                                               \