mei: me: add io register tracing

To make debugging a bit easier we add me register
access tracing
<debugfs>/tracing/events/mei/mei_reg_{read,write}

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>