Fix Python3 Byte and Regex Handling

Convert bytes to strings (utf-8 encoding) to make compatible with
Python3 in arm.py
Use the pattern property to extract the string from the regex pattern,
to pass as a string to tty.expect.
Drop problematic characters when decoding stdout and stderr in misc.py
by setting errors='replace' in the string decode method.

devlib/platform/arm.py

@@ -88,6 +88,9 @@ class VersatileExpressPlatform(Platform):
     def _init_android_target(self, target):
         if target.connection_settings.get('device') is None:
             addr = self._get_target_ip_address(target)
+            if sys.version_info[0] == 3:
+                # Convert bytes to string for Python3 compatibility
+                addr = addr.decode("utf-8")
             target.connection_settings['device'] = addr + ':5555'
 
     def _init_linux_target(self, target):

devlib/utils/misc.py

@@ -179,8 +179,9 @@ def check_output(command, timeout=None, ignore=None, inputtext=None, **kwargs):
     try:
         output, error = process.communicate(inputtext)
         if sys.version_info[0] == 3:
-            output = output.decode(sys.stdout.encoding)
+            # Currently errors=replace is needed as 0x8c throws an error
-            error =  error.decode(sys.stderr.encoding)
+            output = output.decode(sys.stdout.encoding, "replace")
+            error =  error.decode(sys.stderr.encoding, "replace")
     finally:
         if timeout:
             timer.cancel()