pnfs: release lseg in pnfs_generic_pg_cleanup

This is needed to support mirrored writes - the first write can't just
trash the lseg, we need to keep it around until all mirrors have
written.

Signed-off-by: Weston Andros Adamson <dros@primarydata.com>

diff --cc fs/nfs/blocklayout/blocklayout.c
Simple merge

diff --cc fs/nfs/filelayout/filelayout.c
Simple merge

diff --cc fs/nfs/objlayout/objio_osd.c
Simple merge

diff --cc fs/nfs/pnfs.c
Simple merge

diff --cc fs/nfs/pnfs.h
Simple merge