block/io_uring: add missing include file

The commit "Use io_uring_register_ring_fd() to skip fd operations" uses
warn_report but did not include the header file "qemu/error-report.h".
This causes "error: implicit declaration of function ‘warn_report’".
Include this header file.

Fixes: e2848bc5 ("Use io_uring_register_ring_fd() to skip fd operations")
Signed-off-by: Jinhao Fan <fanjinhao21s@ict.ac.cn>
Message-Id: <20220721065645.577404-1-fanjinhao21s@ict.ac.cn>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>