posix: semaphore: explicitly ignore return of k_mutex_unlock()

The nsem_list_unlock() static inline function looks as though it
was designed to always ignore the return value of
k_mutex_unlock(), presumably for performance reasons.

A quick audit of the code looks as though the call should
always succeed.

Prepend (void) to the call to avoid the coverity defect in the
future.

CID 444386

Signed-off-by: Chris Friedt <[email protected]>

Author: cfriedt

lib/posix/options/semaphore.c

@@ -33,7 +33,7 @@ static inline void nsem_list_lock(void)
 
 static inline void nsem_list_unlock(void)
 {
-	k_mutex_unlock(&nsem_mutex);
+	(void)k_mutex_unlock(&nsem_mutex);
 }
 
 static struct nsem_obj *nsem_find(const char *name)