fsverity: stop using PG_error to track error status

As a step towards freeing the PG_error flag for other uses, change ext4
and f2fs to stop using PG_error to track verity errors.  Instead, if a
verity error occurs, just mark the whole bio as failed.  The coarser
granularity isn't really a problem since it isn't any worse than what
the block layer provides, and errors from a multi-page readahead aren't
reported to applications unless a single-page read fails too.

f2fs supports compression, which makes the f2fs changes a bit more
complicated than desired, but the basic premise still works.

Note: there are still a few uses of PageError in f2fs, but they are on
the write path, so they are unrelated and this patch doesn't touch them.

Reviewed-by: Chao Yu <chao@kernel.org>
Acked-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20221129070401.156114-1-ebiggers@kernel.org