nfs: add a new NFS4_OPEN_RESULT_MAY_NOTIFY_LOCK constant

As defined in RFC 5661, section 18.16.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

include/uapi/linux/nfs4.h

@@ -39,8 +39,9 @@
 #define NFS4_FH_VOL_MIGRATION		0x0004
 #define NFS4_FH_VOL_RENAME		0x0008
 
-#define NFS4_OPEN_RESULT_CONFIRM 0x0002
-#define NFS4_OPEN_RESULT_LOCKTYPE_POSIX 0x0004
+#define NFS4_OPEN_RESULT_CONFIRM		0x0002
+#define NFS4_OPEN_RESULT_LOCKTYPE_POSIX		0x0004
+#define NFS4_OPEN_RESULT_MAY_NOTIFY_LOCK	0x0020
 
 #define NFS4_SHARE_ACCESS_MASK	0x000F
 #define NFS4_SHARE_ACCESS_READ	0x0001