mm/slab_common: Remove the unneeded result variable

Return the value from __kmem_cache_shrink() directly instead of storing it
 in another redundant variable.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Acked-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

mm/slab_common.c

@@ -495,13 +495,9 @@ EXPORT_SYMBOL(kmem_cache_destroy);
  */
 int kmem_cache_shrink(struct kmem_cache *cachep)
 {
-	int ret;
-
-
 	kasan_cache_shrink(cachep);
-	ret = __kmem_cache_shrink(cachep);
 
-	return ret;
+	return __kmem_cache_shrink(cachep);
 }
 EXPORT_SYMBOL(kmem_cache_shrink);