Crypto: minor fixes/refactor of AES-NI runtime check

[anonimal]

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Successfully tested on both aesni enabled/disabled machines.

• static const for global bool type
  • static is implied because this particular const type
    exists in namespace but static const appears 'const correct'
• Log to debug channel, not info
• Refactor if/else + type names for clarity
• Add TODO for ARM support

References #285