lib/percpu_counter.c: use helper macro abs()

Use helper macro abs() to simplify the "x >= t || x <= -t" cmp.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/20200927122746.5964-1-linmiaohe@huawei.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/percpu_counter.c

@@ -85,7 +85,7 @@ void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount, s32 batch)
 
 	preempt_disable();
 	count = __this_cpu_read(*fbc->counters) + amount;
-	if (count >= batch || count <= -batch) {
+	if (abs(count) >= batch) {
 		unsigned long flags;
 		raw_spin_lock_irqsave(&fbc->lock, flags);
 		fbc->count += count;