IB/mlx5: Fix unreg_umr to ignore the mkey state

Fix unreg_umr to ignore the mkey state and do not fail if was freed.  This
prevents a case that a user space application already changed the mkey
state to free and then the UMR operation will fail leaving the mkey in an
inappropriate state.

Link: https://lore.kernel.org/r/20190723065733.4899-3-leon@kernel.org
Cc: <stable@vger.kernel.org> # 3.19
Fixes: 968e78dd96 ("IB/mlx5: Enhance UMR support to allow partial page table update")
Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Reviewed-by: Artemy Kovalyov <artemyko@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/mlx5/mlx5_ib.h

@@ -481,6 +481,7 @@ struct mlx5_umr_wr {
 	u64				length;
 	int				access_flags;
 	u32				mkey;
+	u8				ignore_free_state:1;
 };
 
 static inline const struct mlx5_umr_wr *umr_wr(const struct ib_send_wr *wr)