kernel: semaphore: k_sem_init error checking

Check for errors at runtime and stop depending on ASSERTs.
This changes the API for
- k_sem_init

k_sem_init now returns -EINVAL on invalid data.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

include/kernel.h

@@ -3443,10 +3443,12 @@ struct k_sem {
  * @param initial_count Initial semaphore count.
  * @param limit Maximum permitted semaphore count.
  *
- * @return N/A
+ * @retval 0 Semaphore created successfully
+ * @retval -EINVAL Invalid values
+ *
  * @req K-SEM-001
  */
-__syscall void k_sem_init(struct k_sem *sem, unsigned int initial_count,
+__syscall int k_sem_init(struct k_sem *sem, unsigned int initial_count,
 			  unsigned int limit);
 
 /**