MIPS: Fix build errors in sc-mips.c

MIPS: Fix build errors in sc-mips.c

Seen with malta_defconfig on Linus' tree:

  CC      arch/mips/mm/sc-mips.o
arch/mips/mm/sc-mips.c: In function 'mips_sc_is_activated':
arch/mips/mm/sc-mips.c:77: error: 'config2' undeclared (first use in this function)
arch/mips/mm/sc-mips.c:77: error: (Each undeclared identifier is reported only once
arch/mips/mm/sc-mips.c:77: error: for each function it appears in.)
arch/mips/mm/sc-mips.c:81: error: 'tmp' undeclared (first use in this function)
make[2]: *** [arch/mips/mm/sc-mips.o] Error 1
make[1]: *** [arch/mips/mm] Error 2
make: *** [arch/mips] Error 2

[Ralf: Cosmetic changes to minimize the number of arguments passed to
mips_sc_is_activated]

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/1752/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>