move all struct request releated code out of blk-core.c (rebased)

[Christoph Hellwig]

Hi Jens,

this series (against the for-5.16/passthrough-flag branch) removes the
remaining struct request related code from blk-core.c and cleans up a
few related bits around that.

Diffstat:
 b/block/Makefile            |    2 
 b/block/blk-core.c          |  341 --------------------------
 b/block/blk-mq.c            |  573 ++++++++++++++++++++++++++++++++++++--------
 b/block/blk-mq.h            |    3 
 b/block/blk.h               |   33 --
 b/drivers/mtd/mtd_blkdevs.c |   10 
 b/drivers/mtd/ubi/block.c   |    6 
 b/drivers/scsi/scsi_lib.c   |   42 +++
 b/include/linux/blk-mq.h    |   13 
 block/blk-exec.c            |  116 --------
 10 files changed, 552 insertions(+), 587 deletions(-)