lenovo/t530: Be safe by disabling blink gpio hw with a writeout

This disables the blink hardware as it seems to be in the dump. This is
safer as it does not rely on 0 as the reset value when '0x00040000' is
the default according to the util/inteltool. As seen:

gpiobase+0x0018: 0x00040000 (GPO_BLINK) DIFF

Change-Id: Ia1fde108bf3752484f5e991600c435f776af0ced
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/6436
Tested-by: build bot (Jenkins)
Reviewed-by: Vladimir Serbinenko <phcoder@gmail.com>