serial.c: be more pedantic

Check more return codes and close the file handle in case of errors in
sp_openserport().

Corresponding to flashrom svn r1664.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
1 file changed