[PATCH v2]mempool.c : clean up type-casting twice

["Figo.zhang" <figo1802@gmail.com>]

clean up type-casting twice. "size_t" typedef as "unsigned long" in 64-bit system,
and "unsigned int" in 32-bit system.

Signed-off-by: Figo.zhang <figo1802@gmail.com>
---   
mm/mempool.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/mempool.c b/mm/mempool.c
index a46eb1b..bd22982 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -303,7 +303,7 @@ EXPORT_SYMBOL(mempool_free_slab);
  */
 void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
 {
-	size_t size = (size_t)(long)pool_data;
+	size_t size = (size_t) pool_data;
 	return kmalloc(size, gfp_mask);
 }
 EXPORT_SYMBOL(mempool_kmalloc);