LU-6499 obdclass: obdclass module cleanup upon load error

LU-6499 obdclass: obdclass module cleanup upon load error

Fix obdclass_init() error paths to proceed with cleanup.
This will particularly allow to no longer crash upon next
load attempt and this due to previous miscdevice not been
deregistered and thus still referenced in misc_list when
unmapped.

conf-sanity/test_102 has been created to verify correct
behavior/cleanup.

Signed-off-by: Bruno Faccini <bruno.faccini@intel.com>
Change-Id: I6f65cf651251cf92427e2bab3ff6b51ebb98d699
Reviewed-on: https://review.whamcloud.com/22544
Reviewed-by: Patrick Farrell <paf@cray.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>