CIFS: let ses->ipc_tid hold smb2 TreeIds

the TreeId field went from 2 bytes in CIFS to 4 bytes in SMB2+. this
commit updates the size of the ipc_tid field of a cifs_ses, which was
still using 2 bytes.
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/cifsglob.h

@@ -822,7 +822,7 @@ struct cifs_ses {
 	int ses_count;		/* reference counter */
 	enum statusEnum status;
 	unsigned overrideSecFlg;  /* if non-zero override global sec flags */
-	__u16 ipc_tid;		/* special tid for connection to IPC share */
+	__u32 ipc_tid;		/* special tid for connection to IPC share */
 	char *serverOS;		/* name of operating system underlying server */
 	char *serverNOS;	/* name of network operating system of server */
 	char *serverDomain;	/* security realm of server */