ipv6: Fix inet6_csk_bind_conflict so it builds with user namespaces enabled

ipv6: Fix inet6_csk_bind_conflict so it builds with user namespaces enabled

When attempting to build linux-next with user namespaces enabled I ran
into this fun build error.

  CC      net/ipv6/inet6_connection_sock.o
.../net/ipv6/inet6_connection_sock.c: In function ‘inet6_csk_bind_conflict’:
.../net/ipv6/inet6_connection_sock.c:37:12: error: incompatible types when initializing type ‘int’ using
 type ‘kuid_t’
.../net/ipv6/inet6_connection_sock.c:54:30: error: incompatible type for argument 1 of ‘uid_eq’
.../include/linux/uidgid.h:48:20: note: expected ‘kuid_t’ but argument is of type ‘int’
make[3]: *** [net/ipv6/inet6_connection_sock.o] Error 1
make[2]: *** [net/ipv6] Error 2
make[2]: *** Waiting for unfinished jobs....

Using kuid_t instead of int to hold the uid fixes this.

Cc: Tom Herbert <therbert@google.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>