mm/zswap.c: remove unnecessary parentheses

Fix following trivial checkpatch error:

  ERROR: return is not a function, parentheses are not required
Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Acked-by: Seth Jennings <sjennings@variantweb.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/zswap.c

@@ -204,7 +204,7 @@ static struct kmem_cache *zswap_entry_cache;
 static int zswap_entry_cache_create(void)
 {
 	zswap_entry_cache = KMEM_CACHE(zswap_entry, 0);
-	return (zswap_entry_cache == NULL);
+	return zswap_entry_cache == NULL;
 }
 
 static void zswap_entry_cache_destory(void)
@@ -408,8 +408,8 @@ static int zswap_cpu_init(void)
 **********************************/
 static bool zswap_is_full(void)
 {
-	return (totalram_pages * zswap_max_pool_percent / 100 <
-		zswap_pool_pages);
+	return totalram_pages * zswap_max_pool_percent / 100 <
+		zswap_pool_pages;
 }
 
 /*********************************