NFSv4/pNFS: Remove dead code

Since commit 2b28a7bee4 ("fs, nfs: convert
pnfs_layout_hdr.plh_refcount from atomic_t to refcount_t") it has not
been legal to bump a zero refcount, so the code that tries to allow it
if the NFS_LSEG_VALID flag is still set would cause trouble. Luckily,
NFS_LSEG_VALID has its own refcount so we can never hit this bad code
snippet in practice. Remove it to avoid confusion.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/pnfs.c

@@ -596,10 +596,6 @@ pnfs_put_lseg(struct pnfs_layout_segment *lseg)
 	inode = lo->plh_inode;
 
 	if (refcount_dec_and_lock(&lseg->pls_refcount, &inode->i_lock)) {
-		if (test_bit(NFS_LSEG_VALID, &lseg->pls_flags)) {
-			spin_unlock(&inode->i_lock);
-			return;
-		}
 		pnfs_get_layout_hdr(lo);
 		pnfs_layout_remove_lseg(lo, lseg);
 		if (pnfs_cache_lseg_for_layoutreturn(lo, lseg))