sitara: Package keys required for signing boot firmware

The AM625 and similiar SoCs require set boot firmware blobs to be built which include, among other things, the U-Boot SPL binaries. Depending on the variant, one of two keys needs to be used to sign this boot firmware for them to be accepted by the ROM firmware (unless alternative keys are blown into the device in question). The U-Boot source can compile these firmware blobs, however it would require access to the various other components at build time. As some of these components are not suitably licensed to be included in the main Debian repositories we can't assemble them at build time and must do this at a later date.

In recent releases of U-Boot, these keys have been included in the U-Boot source tree. Package the signing keys so that they can be used when the firmware blobs are assembled.

Signed-off-by: Martyn Welch martyn.welch@collabora.com