Don't do NULL-checks before SDL_free()

Replaces the pattern

  if (ptr) {
    SDL_free(ptr);
  }

with

  SDL_free(ptr);

src/core/linux/SDL_evdev_kbd.c

@@ -534,9 +534,7 @@ void SDL_EVDEV_kbd_quit(SDL_EVDEV_keyboard_state *state)
     if (state->key_maps && state->key_maps != default_key_maps) {
         int i;
         for (i = 0; i < MAX_NR_KEYMAPS; ++i) {
-            if (state->key_maps[i]) {
-                SDL_free(state->key_maps[i]);
-            }
+            SDL_free(state->key_maps[i]);
         }
         SDL_free(state->key_maps);
     }

src/core/linux/SDL_ibus.c

@@ -563,9 +563,7 @@ bool SDL_IBus_Init(void)
             return false;
         }
 
-        if (ibus_addr_file) {
-            SDL_free(ibus_addr_file);
-        }
+        SDL_free(ibus_addr_file);
         ibus_addr_file = SDL_strdup(addr_file);
 
         if (inotify_fd < 0) {