mainboard/lenovo/g505s/buildOpts.c: Trivial variable rename

Minor fix to avoid confusion, nothing to see here.

Change-Id: I89d56a91d2df049e85cf49c23218620caba84880
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/7654
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>