tree 320e07397be071aeb0ff847ffc8a3a0494f6affa
parent 2d72bdd6a5273902b47968ec60c73de509341041
author Lei YU <yulei.sh@bytedance.com> 1674025625 +0800
committer Patrick Williams <patrick@stwcx.xyz> 1679325207 +0000

phosphor-image-signing: Add SIGNING_PUBLIC_KEY

Add SIGNING_PUBLIC_KEY so that it installs the public key to the BMC
image.
If it's defined, the user shall not define SIGNING_KEY.

Tested:
* Do not define SIGNING_KEY or SIGNING_PUBLIC_KEY, the build is the same
as before;
* Define SIGNING_PUBLIC_KEY and do not define SIGNING_KEY, the build
installs the SIGNING_PUBLIC_KEY into the BMC image;
* Define SIGNING_KEY and do not define SIGNING_PUBLIC_KEY, the build
installs the public key from SIGNING_KEY;
* Define both SIGNING_PUBLIC_KEY and SIGNING_KEY, the build fails with
below error message:

```
Both SIGNING_KEY and SIGNING_PUBLIC_KEY are defined, expecting only one
```

Signed-off-by: Lei YU <yulei.sh@bytedance.com>
Change-Id: I3f345cc90b82f8964c2b498e8d9616cb20cd65cd