ublk: call ublk_dispatch_req() for handling UBLK_U_IO_NEED_GET_DATA

ublk: call ublk_dispatch_req() for handling UBLK_U_IO_NEED_GET_DATA

We call io_uring_cmd_complete_in_task() to schedule task_work for handling
UBLK_U_IO_NEED_GET_DATA.

This way is really not necessary because the current context is exactly
the ublk queue context, so call ublk_dispatch_req() directly for handling
UBLK_U_IO_NEED_GET_DATA.

Fixes: 216c8f5ef0f2 ("ublk: replace monitor with cancelable uring_cmd")
Tested-by: Jared Holzman <jholzman@nvidia.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250425013742.1079549-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>