ipsec: esp-decrypt rework

Change-Id: Icf83c876d0880d1872b84e0a3d34be654b76149f
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/vnet/ipsec/esp.h b/src/vnet/ipsec/esp.h
index 6ba2e7c..0f75d54 100644
--- a/src/vnet/ipsec/esp.h
+++ b/src/vnet/ipsec/esp.h
@@ -56,6 +56,7 @@
 
 #define ESP_SEQ_MAX		(4294967295UL)
 #define ESP_MAX_BLOCK_SIZE	(16)
+#define ESP_MAX_IV_SIZE		(16)
 #define ESP_MAX_ICV_SIZE	(16)
 
 u8 *format_esp_header (u8 * s, va_list * args);