Define a new gb_module trace point event class, used to trace events associated with the interface abstraction. Define four basic trace points for this--creation time, drop of last reference, before registring interfaces and after de-registering them. In addition, define traces for activating and deactivating, and enabling and disabling an interface. Signed-off-by: Alex Elder <elder@linaro.org> Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>