Remove IOCQE_FLAG_CACHEHIT

This cache hint has been removed from the io_uring series, as there's
some hesitation to leak this information to userspace. Remove it from
the header file and the man page. We can always re-introduce it later,
if we get some variant of this included.

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

src/io_uring.h

@@ -69,11 +69,6 @@ struct io_uring_cqe {
 	__u32	flags;
 };
 
-/*
- * io_uring_event->flags
- */
-#define IOCQE_FLAG_CACHEHIT	(1U << 0)	/* IO did not hit media */
-
 /*
  * Magic offsets for the application to mmap the data it needs
  */