sync io_uring.h API file with Linux 5.13
sync io_uring.h API file with Linux 5.13

Add resource tagging and registation and multi-polling definitions, and
align space/tabs with the kernel.

Signed-off-by: Pavel Begunkov <8608d41fe50396a9dbd36e830be65ba791e26c05@gmail.com>
Link: https://lore.kernel.org/r/bcbe41f61f22d500b30d64335bdd74f249e64d40.1620404433.git.8608d41fe50396a9dbd36e830be65ba791e26c05@gmail.com
Signed-off-by: Jens Axboe <cd8c6775e60d6f67a6984377324e5290df3d5358@kernel.dk>

axboe/liburing,axboe/liburing,axboe/liburing