ip tunnel: fix 'ip -oneline tunnel show' for some GRE tunnels

'ip -oneline tunnel show' was not "oneline" for GRE tunnels with iseq:
# ip tun add gre_test remote 1.1.1.1 local 2.2.2.2 mode gre iseq oseq
# ip -oneline tun show gre_test | wc -l
2

The problem existed because of a typo: '\n' was printed when it shouldn't be.
Fixed.

Signed-off-by: Dmitry Popov <ixaphire@qrator.net>
diff --git a/ip/ip6tunnel.c b/ip/ip6tunnel.c
index 4b73ec6..b83534e 100644
--- a/ip/ip6tunnel.c
+++ b/ip/ip6tunnel.c
@@ -117,7 +117,7 @@
 		}
 
 		if (p->i_flags&GRE_SEQ)
-			printf("%s  Drop packets out of sequence.\n", _SL_);
+			printf("%s  Drop packets out of sequence.", _SL_);
 		if (p->i_flags&GRE_CSUM)
 			printf("%s  Checksum in received packet is required.", _SL_);
 		if (p->o_flags&GRE_SEQ)