MIPS: Fix build error due to unused variables.

c861519f ("MIPS: Fix delay loops which may
be removed by GCC.") which made it upstream was an outdated version of the
patch and is lacking some the removal of two variables that became unused
thus resulting in further warnings and build breakage.  The commit
from ae878615d7cee5d7346946cf1ae1b60e427013c2 was correct however.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>