net: sock: Use USEC_PER_SEC macro instead of literal 1000000

The USEC_PER_SEC is used once in sock_set_timeout as the max value of
tv_usec. But there are other similar codes which use the literal
1000000 in this file.
It is minor cleanup to keep consitent.
Signed-off-by: Gao Feng <fgao@ikuai8.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/sock.c

@@ -367,7 +367,7 @@ static int sock_set_timeout(long *timeo_p, char __user *optval, int optlen)
 	if (tv.tv_sec == 0 && tv.tv_usec == 0)
 		return 0;
 	if (tv.tv_sec < (MAX_SCHEDULE_TIMEOUT/HZ - 1))
-		*timeo_p = tv.tv_sec*HZ + (tv.tv_usec+(1000000/HZ-1))/(1000000/HZ);
+		*timeo_p = tv.tv_sec * HZ + DIV_ROUND_UP(tv.tv_usec, USEC_PER_SEC / HZ);
 	return 0;
 }
 
@@ -1146,7 +1146,7 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
 			v.tm.tv_usec = 0;
 		} else {
 			v.tm.tv_sec = sk->sk_rcvtimeo / HZ;
-			v.tm.tv_usec = ((sk->sk_rcvtimeo % HZ) * 1000000) / HZ;
+			v.tm.tv_usec = ((sk->sk_rcvtimeo % HZ) * USEC_PER_SEC) / HZ;
 		}
 		break;
 
@@ -1157,7 +1157,7 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
 			v.tm.tv_usec = 0;
 		} else {
 			v.tm.tv_sec = sk->sk_sndtimeo / HZ;
-			v.tm.tv_usec = ((sk->sk_sndtimeo % HZ) * 1000000) / HZ;
+			v.tm.tv_usec = ((sk->sk_sndtimeo % HZ) * USEC_PER_SEC) / HZ;
 		}
 		break;