decodetree: Tidy error_with_file

Use proper varargs to print the arguments.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

scripts/decodetree.py

@@ -51,23 +51,27 @@ def error_with_file(file, lineno, *args):
     global output_file
     global output_fd
 
+    prefix = ''
+    if file:
+        prefix += '{0}:'.format(file)
     if lineno:
-        r = '{0}:{1}: error:'.format(file, lineno)
-    elif input_file:
-        r = '{0}: error:'.format(file)
-    else:
-        r = 'error:'
-    for a in args:
-        r += ' ' + str(a)
-    r += '\n'
-    sys.stderr.write(r)
+        prefix += '{0}:'.format(lineno)
+    if prefix:
+        prefix += ' '
+    print(prefix, end='error: ', file=sys.stderr)
+    print(*args, file=sys.stderr)
+
     if output_file and output_fd:
         output_fd.close()
         os.remove(output_file)
     exit(1)
+# end error_with_file
+
 
 def error(lineno, *args):
-    error_with_file(input_file, lineno, args)
+    error_with_file(input_file, lineno, *args)
+# end error
+
 
 def output(*args):
     global output_fd