ip: Move INFINITY_LIFE_TIME to addrconf.h.

INFINITY_LIFE_TIME is the common value used in IPv4 and IPv6 but defined
in both .c files.

Also, 0xffffffff used in addrconf_timeout_fixup() is INFINITY_LIFE_TIME.

Let's move INFINITY_LIFE_TIME's definition to addrconf.h
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20240809235406.50187-6-kuniyu@amazon.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/addrconf.h

@@ -187,10 +187,12 @@ static inline int addrconf_ifid_eui48(u8 *eui, struct net_device *dev)
 	return 0;
 }
 
+#define INFINITY_LIFE_TIME 0xFFFFFFFF
+
 static inline unsigned long addrconf_timeout_fixup(u32 timeout,
 						   unsigned int unit)
 {
-	if (timeout == 0xffffffff)
+	if (timeout == INFINITY_LIFE_TIME)
 		return ~0UL;
 
 	/*

net/ipv4/devinet.c

@@ -703,8 +703,6 @@ static int inet_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh,
 	return err;
 }
 
-#define INFINITY_LIFE_TIME	0xFFFFFFFF
-
 static void check_lifetime(struct work_struct *work)
 {
 	unsigned long now, next, next_sec, next_sched;

net/ipv6/addrconf.c

@@ -92,8 +92,6 @@
 #include <linux/export.h>
 #include <linux/ioam6.h>
 
-#define	INFINITY_LIFE_TIME	0xFFFFFFFF
-
 #define IPV6_MAX_STRLEN \
 	sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")