NFSv4/pNFS: Clear NFS_INO_LAYOUTCOMMIT in pnfs_mark_layout_stateid_invalid

NFSv4/pNFS: Clear NFS_INO_LAYOUTCOMMIT in pnfs_mark_layout_stateid_invalid

Fixes a crash when layout is null during this call stack:

write_inode
    -> nfs4_write_inode
        -> pnfs_layoutcommit_inode

pnfs_set_layoutcommit relies on the lseg refcount to keep the layout
around. Need to clear NFS_INO_LAYOUTCOMMIT otherwise we might attempt
to reference a null layout.

Fixes: fe1cf9469d7bc ("pNFS: Clear all layout segment state in pnfs_mark_layout_stateid_invalid")
Signed-off-by: Jonathan Curley <jcurley@purestorage.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>