clatd: remove spurious MTU_DELTA define

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ic7e24b6b14a74d0a8ef994c2831d5fed42b04edb
diff --git a/clatd.c b/clatd.c
index e10bda1..21ec0d7 100644
--- a/clatd.c
+++ b/clatd.c
@@ -50,9 +50,6 @@
 
 struct clat_config Global_Clatd_Config;
 
-/* 40 bytes IPv6 header - 20 bytes IPv4 header + 8 bytes fragment header */
-#define MTU_DELTA 28
-
 volatile sig_atomic_t running = 1;
 
 int ipv6_address_changed(const char *interface) {