net: decnet: use time_is_before_jiffies() instead of open coding it

Use the helper function time_is_{before,after}_jiffies() to improve
code readability.

Signed-off-by: Wang Qing <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/decnet/dn_nsp_out.c

···
 #include <linux/init.h>
 #include <linux/poll.h>
 #include <linux/if_packet.h>
+#include <linux/jiffies.h>
 #include <net/neighbour.h>
 #include <net/dst.h>
 #include <net/flow.h>
···
 	 * Slow start: If we have been idle for more than
 	 * one RTT, then reset window to min size.
 	 */
-	if ((jiffies - scp->stamp) > t)
+	if (time_is_before_jiffies(scp->stamp + t))
 		scp->snd_window = NSP_MIN_WINDOW;
 
 	if (oth)