spl: reorder the assignment of board info to global data

Move the assignment of board info to global data a bit early which is
safe,
so that ram details can be used to enable caches.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Ravi Babu <ravibabu@ti.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>