staging: ozwpan: Added event logging support

The event logging subsystem allows internal events in the driver to
be logged. This facilitates testing the correct operation of the
driver. This subsystem is optional and can be switched out at
compile time.

Signed-off-by: Chris Kelly <ckelly@ozmodevices.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>