LU-4200 mgs: fix counting of mgs exports

LU-4200 mgs: fix counting of mgs exports

In only_mgs_is_running iterate over mgs exports and only count
non-self and non MDS-MDS exports.

Signed-off-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Change-Id: I145d897fe2f222dae5e998de322ea58ac9f75375
Reviewed-on: http://review.whamcloud.com/9650
Tested-by: Jenkins
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>