MIPS: locking/atomic: Fix atomic{_64,}_sub_if_positive

This looks like a typo and that caused atomic64 test failed.

Signed-off-by: Rui Wang <[e-mail]>
Signed-off-by: Thomas Bogendoerfer <[e-mail]>

arch/mips/include/asm/atomic.h

···
  * The function returns the old value of @v minus @i.
  */
 #define ATOMIC_SIP_OP(pfx, type, op, ll, sc)				\
-static __inline__ int arch_##pfx##_sub_if_positive(type i, pfx##_t * v)	\
+static __inline__ type arch_##pfx##_sub_if_positive(type i, pfx##_t * v)	\
 {									\
 	type temp, result;						\
 									\