The _log() functions, as well as the LogMessage constructor, exist in
two versions, one that takes a log category, and one that doesn't. The
latter uses the default log category. This can be simplified by passing
a LogCategory pointer to _log(), which can then be null for the default
category, and moving the retrieval of the default log category from the
LogMessage constructor to the _log() function.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Sebastian Fricke <sebastian.fricke@posteo.net>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>