NFSv4: Always ask for type with READDIR

Again we have claimed regressions for walking a directory tree, this time
with the "find" utility which always tries to optimize away asking for any
attributes until it has a complete list of entries.  This behavior makes
the readdir plus heuristic do the wrong thing, which causes a storm of
GETATTRs to determine each entry's type in order to continue the walk.

For v4 add the type attribute to each READDIR request to include it no
matter the heuristic.  This allows a simple `find` command to proceed
quickly through a directory tree.

Suggested-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>