debugobjects: Remove redundant NULL pointer check

kmem_cache_destroy() has a built in NULL pointer check, so the one at the
call can be removed.

Signed-off-by: Zhong Jiang <zhongjiang@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <longman@redhat.com>
Cc: <arnd@arndb.de>
Cc: <yang.shi@linux.alibaba.com>
Link: https://lkml.kernel.org/r/1533054298-35824-1-git-send-email-zhongjiang@huawei.com

lib/debugobjects.c

@@ -1188,8 +1188,7 @@ void __init debug_objects_mem_init(void)
 
 	if (!obj_cache || debug_objects_replace_static_objects()) {
 		debug_objects_enabled = 0;
-		if (obj_cache)
-			kmem_cache_destroy(obj_cache);
+		kmem_cache_destroy(obj_cache);
 		pr_warn("out of memory.\n");
 	} else
 		debug_objects_selftest();