block: assert blk_iou_cmd fits in the io_uring_cmd PDU#1012

blktests-ci[bot] wants to merge 2 commits into

linus-master_baselinux-blktests/linux-block:linus-master_basefrom

series/1117340=>linus-masterlinux-blktests/linux-block:series/1117340=>linus-masterCopy head branch name to clipboard