x86,mmiotrace: Add support for tracing STOS instruction

Add support for stos access tracing with mmiotrace.

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Acked-by: Pekka Paalanen <pq@iki.fi>
Cc: Nouveau <nouveau@lists.freedesktop.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20100731205101.GA5860@joi.lan>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>