Let's stay in-sync automatically with Zephyr master by referring
to CONFIGs for the flash device names.
Signed-off-by: Michael Scott <michael.scott@linaro.org>
Move the board specific configurations into its own header file, which
can now be created per board, once it gets tested and validated by the
bootloader.
Signed-off-by: Ricardo Salveti <ricardo.salveti@linaro.org>