Update the signature of dn_dst_gc() to return void instead of int.

This change is required because the .gc member of struct dst_ops was
updated to a void return type in a previous commit [1]. This leads to the
following build error:

net/decnet/dn_route.c:132:10: error: initialization of 'void (*)(struct dst_ops *)' from incompatible pointer type 'int (*)(struct dst_ops *)' [-Werror=incompatible-pointer-types]

Note that dst_alloc() inside net/core/dst.c was already updated to
ignore the return value of this callback.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=af6d10345ca76670c1b7c37799f0d5576ccef277

Fixes: af6d10345ca7 ("ipv6: remove max_size check inline with ipv4")
Signed-off-by: Carlos Bilbao (Lambda) <carlos.bilbao@kernel.org>
---
 net/decnet/dn_route.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index 729d3de6020d..840a0e3852de 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c

@@ -100,7 +100,7 @@ static const int dn_rt_mtu_expires = 10 * 60 * HZ;

 static unsigned long dn_rt_deadline;

-static int dn_dst_gc(struct dst_ops *ops);
+static void dn_dst_gc(struct dst_ops *ops);
 static struct dst_entry *dn_dst_check(struct dst_entry *, __u32);
 static unsigned int dn_dst_default_advmss(const struct dst_entry *dst);
 static unsigned int dn_dst_mtu(const struct dst_entry *dst);

@@ -208,7 +208,7 @@ static void dn_dst_check_expire(struct timer_list *unused)

     mod_timer(&dn_route_timer, now + decnet_dst_gc_interval * HZ);
 }

-static int dn_dst_gc(struct dst_ops *ops)
+static void dn_dst_gc(struct dst_ops *ops)
 {
     struct dn_route *rt;
     struct dn_route __rcu **rtp;

@@ -236,8 +236,6 @@ static int dn_dst_gc(struct dst_ops *ops)

         }
         spin_unlock_bh(&dn_rt_hash_table[i].lock);
     }
-
-    return 0;
 }

 /*
--
2.50.1 (Apple Git-155)