x86/msr: Use the proper trace point conditional for writes

The msr tracing for writes is incorrectly conditional on the read trace.

Fixes: 7f47d8cc

 "x86, tracing, perf: Add trace point for MSR accesses"
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: stable@vger.kernel.org
Cc: ak@linux.intel.com
Link: http://lkml.kernel.org/r/1464976859-21850-1-git-send-email-dgilbert@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>