tap: split gso and checksum offload functionality

Type: refactor

Change-Id: I0d4b79ef384c11c841576d264bfd8ccb21783e10
Signed-off-by: Mohsin Kazmi <sykazmi@cisco.com>
diff --git a/src/vnet/devices/tap/tapv2.api b/src/vnet/devices/tap/tapv2.api
index ec8bd45..861fe17 100644
--- a/src/vnet/devices/tap/tapv2.api
+++ b/src/vnet/devices/tap/tapv2.api
@@ -27,6 +27,7 @@
 
 enum tap_flags {
         TAP_FLAG_GSO = 1,
+        TAP_FLAG_CSUM_OFFLOAD = 2,
 };
 
 /** \brief Initialize a new tap interface with the given parameters