LU-9104 obd: Ignore unknown config param while mounting

LU-9104 obd: Ignore unknown config param while mounting

class_process_proc_param() returns positive value when it encounters
unknown parameters in order to have the below levels process them.
At the very bottom layer the positive value returned by
class_process_proc_param() needs to be dropped.osd_process_config()
missed that, which resulted in target mount failure.

Make sure that osd_process_config() does not return positive value
returned by class_process_proc_param().

Test case has been added to check processing of unknown config
parameters.

Test-Parameters: testlist=conf-sanity
Signed-off-by: Parinay Kondekar <parinay.kondekar@seagate.com>
Signed-off-by: Rahul Deshmukh <rahul.deshmukh@seagate.com>
Seagate-bug-id: MRP-4162
Change-Id: I068b8f2aee4cee69629efc83745d7cb88aea268c
Reviewed-on: https://review.whamcloud.com/25368
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>