intel/fsp_bd82x6x: Fix cycle error some more

As a follow up to #6479 (63e1948643fcbd763c83b6baa6cd9a077d49f1fc),
fix the remaining faulty loop.

Change-Id: I2c77efe620c71e939f4d74e48f90a166c782e5f5
Found-by: Coverity Scan
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/6569
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <gaumless@gmail.com>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>