[PATCH -next] arm64/spinlock: fix a -Wunused-function warning

[Qian Cai]

The commit f5bfdc8e3947 ("locking/osq: Use optimized spinning loop for
arm64") introduced a warning from Clang because vcpu_is_preempted() is
compiled away,

kernel/locking/osq_lock.c:25:19: warning: unused function 'node_cpu'
[-Wunused-function]
static inline int node_cpu(struct optimistic_spin_node *node)
                  ^
1 warning generated.

Since vcpu_is_preempted() had already been defined in
include/linux/sched.h as false, just comment out the redundant macro, so
it can still be served for the documentation purpose.

Fixes: f5bfdc8e3947 ("locking/osq: Use optimized spinning loop for arm64")
Signed-off-by: Qian Cai <cai@xxxxxx>
---
 arch/arm64/include/asm/spinlock.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
index 102404dc1e13..b05f82e8ba19 100644
--- a/arch/arm64/include/asm/spinlock.h
+++ b/arch/arm64/include/asm/spinlock.h
@@ -17,7 +17,8 @@
  *
  * See:
  * https://lore.kernel.org/lkml/20200110100612.GC2827@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+ *
+ * #define vcpu_is_preempted(cpu)	false
  */
-#define vcpu_is_preempted(cpu)	false
 
 #endif /* __ASM_SPINLOCK_H */
-- 
2.21.0 (Apple Git-122.2)