mlx4_core: Move kernel doorbell management into core

In addition to mlx4_ib, there will be ethernet and FC consumers of
mlx4_core, so move the code for managing kernel doorbells into the
core module to avoid having to duplicate this multiple times.

Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/net/mlx4/mlx4.h b/drivers/net/mlx4/mlx4.h
index 7333681..a4023c2 100644
--- a/drivers/net/mlx4/mlx4.h
+++ b/drivers/net/mlx4/mlx4.h
@@ -257,6 +257,9 @@
 	struct list_head	ctx_list;
 	spinlock_t		ctx_lock;
 
+	struct list_head        pgdir_list;
+	struct mutex            pgdir_mutex;
+
 	struct mlx4_fw		fw;
 	struct mlx4_cmd		cmd;