[MIPS] Fix compiler warnings (field width, unused variable)

[MIPS] Fix compiler warnings (field width, unused variable)

Fix following warnings:
linux/arch/mips/kernel/setup.c:432: warning: field width is not type int (arg 2)
linux/arch/mips/kernel/setup.c:432: warning: field width is not type int (arg 4)
linux/arch/mips/kernel/syscall.c:279: warning: unused variable `len'
linux/arch/mips/kernel/syscall.c:280: warning: unused variable `name'
linux/arch/mips/math-emu/dp_fint.c:32: warning: unused variable `xc'
linux/arch/mips/math-emu/dp_flong.c:32: warning: unused variable `xc'
linux/arch/mips/math-emu/sp_fint.c:32: warning: unused variable `xc'
linux/arch/mips/math-emu/sp_flong.c:32: warning: unused variable `xc'

(original patch by Atsushi, slight changes to the setup.c part by me.)

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>