tools headers cpufeatures: Sync with the kernel sources

tools headers cpufeatures: Sync with the kernel sources

To pick the changes from:

  1f21bd33365f471e ("x86/speculation: Rename RETPOLINE_AMD to RETPOLINE_LFENCE")

Its just a comment fixup.

This only causes these perf files to be rebuilt:

  CC       /tmp/build/perf/bench/mem-memcpy-x86-64-asm.o
  CC       /tmp/build/perf/bench/mem-memset-x86-64-asm.o

And addresses this perf build warning:

  Warning: Kernel ABI header at 'tools/arch/x86/include/asm/cpufeatures.h' differs from latest version at 'arch/x86/include/asm/cpufeatures.h'
  diff -u tools/arch/x86/include/asm/cpufeatures.h arch/x86/include/asm/cpufeatures.h

Cc: Borislav Petkov <bp@suse.de>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/lkml/YiyiHatGaJQM7l/Y@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>