Union Station: Remove SIO support

Because the Union Station platform doesn't have an SIO chip,
this commit removes the Fintek SIO support.

Change-Id: Idba4222ce136821dee2530a72d1630eb5ad613a2
Signed-off-by: Frank Vibrans <frank.vibrans@se-eng.com>
Reviewed-on: http://review.coreboot.org/787
Reviewed-by: Peter Stuge <peter@stuge.se>
Tested-by: build bot (Jenkins)
3 files changed