mainboard/*: Use generic winbond romstage in place of w83627thg

Use the generic implementation of winbond in place of the model specific
w83627thg_enable_serial() as so that it maybe removed later.

Change-Id: Ice1a0dc428de9a3ddfb79e877fb03c7a8e09665f
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/5603
Tested-by: build bot (Jenkins)
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
superio/winbond/w83627thg: Remove w83627thg_enable_serial symbol

Remove model specific implementation, w83627thg_enable_serial, from
romstage component of sio support.

Change-Id: I8ef1de5ccccae5f4dba69dbdb939e7070d3cecfc
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/5604
Tested-by: build bot (Jenkins)
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>