mm/slub: minor coding style tweaks

Add whitespace to fix coding style issues, improve code reading.

Link: https://lkml.kernel.org/r/1612847403-5594-1-git-send-email-daizhiyuan@phytium.com.cn
Signed-off-by: Zhiyuan Dai <daizhiyuan@phytium.com.cn>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/slub.c

@@ -3269,7 +3269,7 @@ void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
 		if (!df.page)
 			continue;
 
-		slab_free(df.s, df.page, df.freelist, df.tail, df.cnt,_RET_IP_);
+		slab_free(df.s, df.page, df.freelist, df.tail, df.cnt, _RET_IP_);
 	} while (likely(size));
 }
 EXPORT_SYMBOL(kmem_cache_free_bulk);