flashrom: Add support for Gigabyte GA-MA790FX-DQ6. This board uses IT8718F LPC->SPI translation for the flash chip. Tested by Mateusz Murawski. Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net> Acked-by: Mateusz Murawski <matowy@tlen.pl>