libertas: Update libertas core with GSPI constants

Add GSPI constants to libertas core.

Fix misleading comment in lbs_setup_firmware.

Signed-off-by: Colin McCabe <colin@cozybit.com>
Signed-off-by: Andrey Yurovsky <andrey@cozybit.com>
Acked-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>