[PATCH] btt: Cleaned up patches for SEEK additions, DM, Q2A and seek fixes

[PATCH] btt: Cleaned up patches for SEEK additions, DM, Q2A and seek fixes

Added changes to handle DM devices:

- Used __pad field in struct blk_io_trace_remap to store from device,
  contains partition device information. Required modification in
  blkparse_fmt.c:process_default() to handle this change.

- To better handle DM devices, noted that REMAP traces can refer to other
  REMAP traces, and thus added A_A and A_Q types (much like Q_A and Q_X)
  types.

Signed-off-by: Jens Axboe <axboe@kernel.dk>