[PARISC] fix return type of __atomic64_add_return

The return type of __atomic64_add_return of should be s64 or long, not
int.  This fixes the atomic64 test failure that I previously reported.
Signed-off-by: NJohn David Anglin <dave.anglin@nrc-cnrc.gc.ca>
Cc: stable@kernel.org
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

arch/parisc/include/asm/atomic.h

@@ -259,10 +259,10 @@ static __inline__ int atomic_add_unless(atomic_t *v, int a, int u)
 
 #define ATOMIC64_INIT(i) ((atomic64_t) { (i) })
 
-static __inline__ int
+static __inline__ s64
 __atomic64_add_return(s64 i, atomic64_t *v)
 {
-	int ret;
+	s64 ret;
 	unsigned long flags;
 	_atomic_spin_lock_irqsave(v, flags);