ktime: Cleanup ktime_set() usage

ktime_set(S,N) was required for the timespec storage type and is still
useful for situations where a Seconds and Nanoseconds part of a time value
needs to be converted. For anything where the Seconds argument is 0, this
is pointless and can be replaced with a simple assignment.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>

include/linux/skbuff.h

@@ -3227,7 +3227,7 @@ static inline ktime_t net_timedelta(ktime_t t)
 
 static inline ktime_t net_invalid_timestamp(void)
 {
-	return ktime_set(0, 0);
+	return 0;
 }
 
 struct sk_buff *skb_clone_sk(struct sk_buff *skb);