block: remove bio_start_io_acct_time

bio_start_io_acct_time is not actually used anywhere, so remove it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221025155916.270303-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>