sf: Flash power up read-only based on idcode0

Using macro's for flash power up read-only access code
leads wrong behaviour hence use idcode0 for runtime
detection, hence the flash which require this functionality
gets detected at runtime.

Tested-by: Jagan Teki <jteki@openedev.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Jagan Teki <jteki@openedev.com>