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>

man/io_uring_enter.2

@@ -290,11 +290,7 @@ is copied from the field of the same name in the submission queue
 entry.  The primary use case is to store data that the application
 will need to access upon completion of this particular I/O.  The
 .I flags
-bit mask may contain 0 or more of the following values, ORed together:
-.TP
-.BR IOCQE_FLAG_CACHEHIT
-The page(s) associated with the buffered I/O operation were present in
-the page cache.
+is reserved for future use.
 .I res
 is the operation-specific result.
 .PP

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
  */