Revert "blk-mq: put driver tag when this request is completed"

Revert "blk-mq: put driver tag when this request is completed"

This reverts commits the following commits:

	ed5626e33e73fa7de8d7d6380136a2ed75cece25
	594e47fc0d9922dd7ddeeb7c410222e98cdb8171
	80babf8fb134bb5414ae573ab3cfc9bbf7fb9796

The last one is the culprit, but we have to go a bit deeper to get this
to revert cleanly. There's been a report that this breaks some MMC
setups [1], and also causes an issue with swap [2]. Until this can be
figured out, revert the offending commits.

[1] https://lore.kernel.org/linux-block/57fb09b1-54ba-f3aa-f82c-d709b0e6b281@samsung.com/
[2] https://lore.kernel.org/linux-block/20200702043721.GA1087@lca.pw/

Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reported-by: Qian Cai <cai@lca.pw>
Signed-off-by: Jens Axboe <axboe@kernel.dk>