mark config as error when parameter's quote is not closed
Switch can download and replace old dot-config with the one containing not closed quote as a parameter's value.
dot-config with the line like:
CONFIG_PORT04_PARAMS="name=
Will replace current dot-config. However, it will cause errors during
the next boot since such dot-config cannot be sourced by the start-up
scripts. By this, faulty dot-config cannot be replaced by redownloaded
dot-config. Dot-config has to be fixed manually.