arm: allow CONFIG_LINUX_KERNEL_IMAGE_HEADER to be set in defconfig

Let this option be enabled dynamically for boards that support multiple
mechanisms for booting U-Boot (e.g. as a first-stage or chainloaded
bootloader).

Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
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This patch has no dependencies

Cc: Simon Glass <sjg@chromium.org>
1 file changed