block: simplify ioc_lookup_icq

Remove the ioc argument as it always points to current->io_context.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-15-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>