regmap: replace kmalloc with kmalloc_array

Replace kmalloc with specialized function kmalloc_array when the size
is a multiplication of : number * size

Signed-off-by: lixiubo <lixiubo@cmss.chinamobile.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/base/regmap/regcache-rbtree.c

@@ -361,8 +361,8 @@ regcache_rbtree_node_alloc(struct regmap *map, unsigned int reg)
 		rbnode->base_reg = reg;
 	}
 
-	rbnode->block = kmalloc(rbnode->blklen * map->cache_word_size,
-				GFP_KERNEL);
+	rbnode->block = kmalloc_array(rbnode->blklen, map->cache_word_size,
+				      GFP_KERNEL);
 	if (!rbnode->block)
 		goto err_free;