dbus-sdr: treat FRUs with a chassis type of "Main Server" as baseboards

Previously this had been restricted to "rack mount" only; the ASRock
Rack E3C246D4I board's FRU EEPROM has it marked as a "main server",
however, so this lets that FRU data get used for FRU ID zero (baseboard
info).

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Change-Id: Iff59b30afcc9fbe1cde15358adfabd37152acd1d
1 file changed