Fix remap handling by blktrace

Fix remap handling by blktrace

This patch provides more information concerning REMAP operations on block
IOs. The additional information provides clearer details at the user level,
and supports post-processing analysis in btt.

o  Adds in partition remaps on the same device.
o  Fixed up the remap information in DM to be in the right order
o  Sent up mapped-from and mapped-to device information

Signed-off-by: Alan D. Brunelle <alan.brunelle@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>