bsp: Align corstone1000 image configuration with mender

Aligns mender related configuration for Corstone-1000 platform. Additionally, Corstone-1000 capsule key and certificate files are already installed by u-boot recipe and mender build triggers firmware-deploy task again to copy these binaries which causes an issue. So this commits also removes capsule key and certification for Corstone-1000 for mender builds.

Signed-off-by: Emekcan Aras Emekcan.Aras@arm.com