GitLab

Implement serial port shutdown both for regular termination and error
conditions in pony_spi.

Corresponding to flashrom svn r1952.
Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>