tools/mpremote: Fix exec_ -> exec in commands.py.

This was missed in the pyboard refactor and is preventing `cp -r` from working. Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

Author: jimmo

tools/mpremote/mpremote/commands.py

@@ -137,13 +137,13 @@ def _list_recursive(files, path):
  raise CommandError("'cp -r' source files must be local")
  _list_recursive(src_files, path)
  known_dirs = {""}
- state.transport.exec_("import os")
+ state.transport.exec("import os")
  for dir, file in src_files:
  dir_parts = dir.split("/")
  for i in range(len(dir_parts)):
  d = "/".join(dir_parts[: i + 1])
  if d not in known_dirs:
- state.transport.exec_(
+ state.transport.exec(
  "try:\n os.mkdir('%s')\nexcept OSError as e:\n print(e)" % d
  )
  known_dirs.add(d)