ARM: DRA7: emif: Enable interleaving for higher address space

Given that DRA7/OMAP5 SoCs can support more than 2GB of memory,
enable interleaving for this higher memory to increase performance.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>