arm: exynos: Move BL1/2 SPI flash defines to their user, drop CONFIG

These particular values are not configurable and today we always set
CONFIG_SECURE_BL1_ONLY.  Move these to where they're used in the code,
and drop from the CONFIG namespace.

Cc: Minkyu Kang <mk7.kang@samsung.com>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Reviewed-by: Minkyu Kang <mk7.kang@samsung.com>