HID: logitech-hidpp: 2 fixes in hidpp_root_get_protocol_version()

- remove the constant '1'
- when the device is not connected, the protocol error
  HIDPP_ERROR_RESOURCE_ERROR is raised. We should not warn the user about
  it because it is somewhat expected as an answer when we check if the
  device is connected.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>