statx: remove incorrect part of vfs_statx() comment

request_mask and query_flags are function arguments, not passed in
struct kstat.  So remove the part of the comment which claims otherwise.
This was apparently left over from an earlier version of the statx
patch.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>