LU-8837 lod: move lod-specifc pool config code into lod_dev

LU-8837 lod: move lod-specifc pool config code into lod_dev

obd_config.c contains code that only applies to lod devices, for
managing a QMT pool along-side each normal pool.

As this code is specific to lod, it is best to move it into the lod
module.  This is particularly helpful as it removes it from
client-only builds.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I9e0d014a299c28b73e48ce2e06581cb011acce47
Reviewed-on: https://review.whamcloud.com/41993
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>