DAP: fix sending SWJ sequence.

- If the requested protocol was DEFAULT, then that value could be
  passed to the SWJSequenceSender, which would ignore it. Fixed by
  updating the protocol after connecting the probe.
- Also updated SWJSequenceSender to assert on unhandled protocol.

Author: flit

pyocd/coresight/dap.py

@@ -162,6 +162,7 @@ def connect(self, protocol=None):
             else:
                 self._connect_probe(protocol)
 
+            protocol = self._probe.wire_protocol
             self._connect_dp(protocol)
         finally:
             self._probe.unlock()

pyocd/probe/swj.py

@@ -43,6 +43,8 @@ def select_protocol(self, protocol):
             self._switch_to_swd()
         elif protocol == DebugProbe.Protocol.JTAG:
             self._switch_to_jtag()
+        else:
+            assert False, "unhandled protocol %s in SWJSequenceSender" % protocol
 
     def _switch_to_swd(self):
         """! @brief Send SWJ sequence to select SWD."""