[IB] uverbs: Add device-specific ABI version attribute

Add abi_version attribute to uverbs class devices to allow for
ABI versioning of device-specific interfaces.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index e6f4c9e..d13f25a 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -951,6 +951,8 @@
 		IB_DEV_UNREGISTERED
 	}                            reg_state;
 
+	int			     uverbs_abi_ver;
+
 	u8                           node_type;
 	u8                           phys_port_cnt;
 };