Broken build with disabling OpenSSL crypto

[Jernej Škrabec]

Hi everyone!

Commit cb9faa6f98ae ("tools: Use a single target-independent config to enable 
OpenSSL") recently introduced option to disable usage of OpenSSL via 
CONFIG_TOOLS_LIBCRYPTO. However, just a bit later, another commit b4f3cc2c42d9 
("tools: kwbimage: Do not hide usage of secure header under 
CONFIG_ARMADA_38X") made U-Boot tools hard dependent on OpenSSL. That totally 
defeats the purpose of first commit. I suggest that it gets reverted.

I would like disable OpenSSL for my usage, since it gives me troubles when 
cross-compiling U-Boot inside LibreELEC build system. It's not needed for our 
case anyway.

Best regards,
Jernej