NFSv4/pnfs: Reset the layout state after a layoutreturn

[ Upstream commit 6d6d7f91cc8c111d40416ac9240a3bb9396c5235 ]

If there are still layout segments in the layout plh_return_lsegs list
after a layout return, we should be resetting the state to ensure they
eventually get returned as well.

Fixes: 68f74479 ("pNFS: Do not free layout segments that are marked for return")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>