LU-13783 procfs: fix improper prop_ops fields

The lod pool and nodemap proc_ops missed renaming the fields to
start with .proc_*. On newer distros like Ubuntu 20.04 HWE you
get the following compile error:

lustre-release/lustre/ptlrpc/nodemap_lproc.c:686:3: error: ‘const struct proc_ops’ has no member named ‘open’
  686 |  .open   = nodemap_ranges_open,

Test-Parameters: trivial
Fixes: 13cd0f9f667 ("LU-13344 libcfs: Abstract proc_fs with proc_ops")
Signed-off-by: James Simmons <jsimmons@infradead.org>
Change-Id: I5fff7519a801f585690d468255f7ca6c73adcc90
Reviewed-on: https://review.whamcloud.com/43880
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>