LU-10937 sptlrpc: split sptlrpc_process_config()

LU-10937 sptlrpc: split sptlrpc_process_config()

Make sptlrpc_process_config() more than a single line wapper
exporting function. Instead migrate the lcfg parsing out of
__sptlrpc_process_config() so that we can use this function
for both LCFG_PARAM and LCFG_SET_PARAM handling.

The first field parsed from struct lustre_cfg *lcfg is the
target. This can be "_mgs", file system name, or an obd target
i.e fsname-MDT0000. We can move to extracting the file system
name out of the target string using server_name2fsname().

Test-Parameters: testlist=sanity-sec envdefinitions=SHARED_KEY=true

Change-Id: If94ee8164ab2b49fe10d098b32faea9e331f04ac
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/33760
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>