southbridge/amd/cimx/sb800: Unused func smbus_delay()

Change-Id: Icc12aafc1462c08bca77a1798d4fae86b8250708
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/5748
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
Tested-by: build bot (Jenkins)