splice: fix misleading comment

Splice is tied to pipes by design, it'll not change. And now that
the splice stuff is in splice.h (and note pipe.h), the rest of the comment
is out-of-date as well.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

include/linux/splice.h

@@ -11,8 +11,7 @@
 #include <linux/pipe_fs_i.h>
 
 /*
- * splice is tied to pipes as a transport (at least for now), so we'll just
- * add the splice flags here.
+ * Flags passed in from splice/tee/vmsplice
  */
 #define SPLICE_F_MOVE	(0x01)	/* move pages instead of copying */
 #define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */