chimera: query for inode generation on readdir

keep nfs client cache more consistent.
add missing rdev field.

Acked-by: Paul Millar
Target: master, 2.10
Require-book: no
Require-notes: no
(cherry picked from commit 86f6f6b8da0e0350408301f32bd8746c8e52656b)
Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Merge pull request #919 from kofemann/fix-chimera-readdir-2.10

chimera: query for inode generation on readdir