<sys/platform/x86.h>: Add Intel Key Locker support

<sys/platform/x86.h>: Add Intel Key Locker support

Add Intel Key Locker:

https://software.intel.com/content/www/us/en/develop/download/intel-key-locker-specification.html

support to <sys/platform/x86.h>.  Intel Key Locker has

1. KL: AES Key Locker instructions.
2. WIDE_KL: AES wide Key Locker instructions.
3. AESKLE: AES Key Locker instructions are enabled by OS.

Applications should use

if (CPU_FEATURE_USABLE (KL))

and

if (CPU_FEATURE_USABLE (WIDE_KL))

to check if AES Key Locker instructions and AES wide Key Locker
instructions are usable.