Fixes port opening code in async blink demo for pic32mx target that does not support asynchronous IO yet.
Fixes port opening code in async blink demo for pic32mx target that does not support asynchronous IO yet.

bakerstu/openmrn,bakerstu/openmrn,bakerstu/openmrn,bakerstu/openmrn,bakerstu/openmrn,bakerstu/openmrn