Revert "scsi: core: Use a structure member to track the SCSI command submitter"

This reverts commit f2d30198 which is
commit bf23e619 upstream.

As reported, a lot of scsi changes were made just to resolve a 2 line
patch, so let's revert them all and then manually fix up the 2 line
fixup so that things are simpler and potential abi changes are not an
issue.

Link: https://lore.kernel.org/r/ZZ042FejzwMM5vDW@duo.ucw.cz


Reported-by: Pavel Machek <pavel@ucw.cz>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Benjamin Block <bblock@linux.ibm.com>
Cc: Bean Huo <beanhuo@micron.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>