MIPS: Lemote 2f: Enable legacy RTC driver

Currently rtclib is not available on Loongson family machines but the
legacy RTC driver works well on them.  Deselect RTC_LIB to allow the legacy
RTC driver to be selected.

The rtclib patch series

   http://www.linux-mips.org/cgi-bin/mesg.cgi?a=linux-mips&i=a91e34bf2595157830d599cb66becd52247b1819.1257383766.git.wuzhangjin%40gmail.com

or, in patchworks:

   http://patchwork.linux-mips.org/patch/570/
   http://patchwork.linux-mips.org/patch/571/
   http://patchwork.linux-mips.org/patch/572/



is eventually going to switch Lemote platforms to rtclib.

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: zhangfx@lemote.com
Cc: yanh@lemote.com 
Cc: huhb@lemote.com
Cc: Nicholas Mc Guire <hofrat@hofr.at>
Cc: Arnaud Patard <apatard@mandriva.com>
Cc: loongson-dev@googlegroups.com
Cc: linux-mips@linux-mips.org
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>