patman: Avoid circular dependency between command and tools

This seems to cause problems in some cases. Split the dependency by
copying the code to command.

Reported-by: Stefan Bosch <stefan_b@posteo.net>
Signed-off-by: Simon Glass <sjg@chromium.org>

tools/patman/command.py

@@ -5,7 +5,6 @@
 import os
 
 from patman import cros_subprocess
-from patman import tools
 
 """Shell command ease-ups for Python."""
 
@@ -35,9 +34,9 @@ class CommandResult:
 
     def ToOutput(self, binary):
         if not binary:
-            self.stdout = tools.ToString(self.stdout)
-            self.stderr = tools.ToString(self.stderr)
-            self.combined = tools.ToString(self.combined)
+            self.stdout = self.stdout.decode('utf-8')
+            self.stderr = self.stderr.decode('utf-8')
+            self.combined = self.combined.decode('utf-8')
         return self