Do not send SMB2 signatures for SMB3 frames

Restructure code to make SMB2 vs. SMB3 signing a protocol
specific op.  SMB3 signing (AES_CMAC) is not enabled yet,
but this restructuring at least makes sure we don't send
an smb2 signature on an smb3 signed connection. A followon
patch will add AES_CMAC and enable smb3 signing.

Signed-off-by: Steve French <smfrench@gmail.com>
Acked-by: Jeff Layton <jlayton@samba.org>
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 74a07b6..dfab450 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -367,6 +367,8 @@
 	void (*set_lease_key)(struct inode *, struct cifs_fid *fid);
 	/* generate new lease key */
 	void (*new_lease_key)(struct cifs_fid *fid);
+	int (*calc_signature)(struct smb_rqst *rqst,
+				   struct TCP_Server_Info *server);
 };
 
 struct smb_version_values {
@@ -1489,6 +1491,6 @@
 extern struct smb_version_operations smb21_operations;
 extern struct smb_version_values smb21_values;
 #define SMB30_VERSION_STRING	"3.0"
-/*extern struct smb_version_operations smb30_operations; */ /* not needed yet */
+extern struct smb_version_operations smb30_operations;
 extern struct smb_version_values smb30_values;
 #endif	/* _CIFS_GLOB_H */