API: Use string type instead of u8.

The new string type is modelled after string in proto3.
It is always variable length.

Change-Id: I64884067e28a80072c8dac31b7c7c82d6e306051
Signed-off-by: Ole Troan <ot@cisco.com>
Signed-off-by: Michal Cmarada <mcmarada@cisco.com>
Signed-off-by: Ole Troan <ot@cisco.com>

test/framework.py

@@ -918,7 +918,7 @@ class VppTestCase(unittest.TestCase):
     def assert_packet_counter_equal(self, counter, expected_value):
         counters = self.vapi.cli("sh errors").split('\n')
         counter_value = -1
-        for i in range(1, len(counters) - 1):
+        for i in range(1, len(counters)):
             results = counters[i].split()
             if results[1] == counter:
                 counter_value = int(results[0])