block: devirtualize the integrity processing

block: devirtualize the integrity processing

Replace the profile with a simple integer indicating the PI
type and a new flag to signal that any integrity/metadata
processing is enabled and remove the various indirect calls.

To make this work t10-pi.c is not always built into the core kernel
when BLK_DEV_INTEGRITY is enabled, but it is down to a few hundred
lines of code and thus not very efficient when built as a separate
module anyway.

Signed-off-by: Christoph Hellwig <hch@lst.de>