MIPS: Clean up MIPS MT and CMP configuration options.

This patch accomplishes the following:

  * Clean up wording on all MIPS MT configuration menu items.
  * Simplify and neaten up options selected by MIPS_MT_SMP.
  * Make MIPS_MT_SMTC support as deprecated.
  * Make MIPS_CMP support to depend on MIPS_MT_SMP also.
  * Remove redundant options selected by MIPS_CMP.

Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6019/