x86/insn: Add XOP prefix instructions decoder support

x86/insn: Add XOP prefix instructions decoder support

Support decoding AMD's XOP prefix encoded instructions.

These instructions are introduced for Bulldozer micro architecture, and not
supported on Intel's processors. But when compiling kernel with
CONFIG_X86_NATIVE_CPU on some AMD processor (e.g. -march=bdver2), these
instructions can be used.

Closes: https://lore.kernel.org/all/871pq06728.fsf@wylie.me.uk/
Reported-by: Alan J. Wylie <alan@wylie.me.uk>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Alan J. Wylie <alan@wylie.me.uk>
Link: https://lore.kernel.org/175386161199.564247.597496379413236944.stgit@devnote2