MCUBOOT_TARGET_CONFIG is included in several places now,
not just boot/zephyr/main.c. This seems likely to continue.
Let's avoid trouble and make it a real header file, target.h, that
pulls in MCUBOOT_TARGET_CONFIG. That done, include target.h instead
everywhere MCUBOOT_TARGET_CONFIG is included.
This will make it easier to provide values at an SoC/family level
later. We can expect different Zephyr boards to have the same SoC and
thus likely the same mcuboot flash layout, so this will avoid
duplication.
All supported boards are compile-tested.
Signed-off-by: Marti Bolivar <marti.bolivar@linaro.org>
51181cf34f