[MIPS] Sparse: fix sparse for 64-bit kernels.

    
This commit breaks sparse for 64bit kernel.  The -m64 option is
required.  Also, some macro values (such as _MIPS_TUNE, etc.)  contain
double-quote characters so it would be better quoting arguments by
single-quote characters.
    
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>