MIPS: MT: Remove norps command line parameter

The "norps" kernel command line parameter has apparently been deprecated
ever since it was added to the kernel back in 2006 - all it does is
print a message telling the user to use something else.

Remove the long dead "norps" parameter.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/21244/
Cc: linux-mips@linux-mips.org