Revert "blk-mq: remove code for dealing with remapping queue"

Revert "blk-mq: remove code for dealing with remapping queue"

This reverts commit 37c7c6c76d431dd7ef9c29d95f6052bd425f004c.

Turns out some drivers(most are FC drivers) may not use managed
IRQ affinity, and has their customized .map_queues meantime, so
still keep this code for avoiding regression.

Reported-by: Laurence Oberman <[email protected]>
Tested-by: Laurence Oberman <[email protected]>
Tested-by: Christian Borntraeger <[email protected]>
Tested-by: Stefan Haberland <[email protected]>
Cc: Ewan Milne <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Sagi Grimberg <[email protected]>
Signed-off-by: Ming Lei <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>