Add ability to configure offload features

Change-Id: I5c63fd6856a3fabb1a1c2b850c7e12d4d0815114

linux/map.jinja

@@ -141,6 +141,13 @@
     'maxwait',
     'stp',
     'gro',
+    'rx',
+    'tx',
+    'sg',
+    'tso',
+    'ufo',
+    'gso',
+    'lro',
     'lacp_rate',
     'ad_select',
     'downdelay',