x86/cpufeatures: Flip the /proc/cpuinfo appearance logic

I'm getting tired of telling people to put a magic "" in the

  #define X86_FEATURE		/* "" ... */

comment to hide the new feature flag from the user-visible
/proc/cpuinfo.

Flip the logic to make it explicit: an explicit "<name>" in the comment
adds the flag to /proc/cpuinfo and otherwise not, by default.

Add the "<name>" of all the existing flags to keep backwards
compatibility with userspace.

There should be no functional changes resulting from this.

Acked-by: Dave Hansen <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: bp3tk0v