lenovo/t530/mainboard.c: Add EC info to SMBIOS

As is in:
91175bb lenovo/x201 & x230: Add EC info to SMBIOS

This is needed for the Linux driver for the Lenovo's to properly attach.

Change-Id: Ib910b25f392d9d3d6362b6909ce9fd4eeae9a096
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/6399
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>