LU-11961 nodemap: nodemap_create() handles default nodemap

LU-11961 nodemap: nodemap_create() handles default nodemap

nodemap_create() is responsible for assigning nmc_default_nodemap
so it should not be done outside of this function.

Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I8d0615196e32fb8e6c59ddedd421323a7d6eff7f
Reviewed-on: https://review.whamcloud.com/34245
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Jeremy Filizetti <jeremy.filizetti@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>