blktrace: add definitions for struct blk_io_trace2

blktrace: add definitions for struct blk_io_trace2

Add definitions for the extended version of the blktrace protocol using a
wider action type to be able to record new actions in the kernel.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>