arm: da850-evm: Enable MTD Parts in SPI Flash

There is a discrepency between U-Boot and Linux on the partition map.
This enabes the MTD parts to pass MTD partition information from U-Boot to
Linux.  Linux already has a pending patch to enable MTD PARTS in
davinci_all_defconfig

Reviewed-by: Jagan Teki <jagan@openedev.com>
Signed-off-by: Adam Ford <aford173@gmail.com>