LU-10467 target: remove lwi arg from target_bulk_io

LU-10467 target: remove lwi arg from target_bulk_io

The callers of target_bulk_io() pass in an lwi pointer but never put
any information into it or take any information out of it.  Also
target_bulk_io() always re-initializes the struct before using it, so
it doesn't communicate info from one call to the next.

All that this achieves it to make stack usage slightly less
in the few cases where the lwi pointer is tti_wait_info in
struct tgt_thread_info.  That is not worth it, and a future
patch will remove the use of the struct completely.

So make lwi local to target_bulk_io, and remove it from
all callers.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.com>
Change-Id: Ib6039006d0168393abf3995877acde2d7c796b1f
Reviewed-on: https://review.whamcloud.com/35969
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>