cifs: merge __{cifs,smb2}_reconnect[_tcon]() into cifs_tree_connect()

They were identical execpt to CIFSTCon() vs. SMB2_tcon().
These are also available via ops->tree_connect().

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>