LU-4304 tests: fix auster to detect "SKIP" test status

LU-4304 tests: fix auster to detect "SKIP" test status

This patch fixes run_suite() in auster to detect "SKIP"
test status for one test suite. If all of the sub-tests
in one test suite were skipped, then the status of the
test suite would be "SKIP" instead of "PASS".

Signed-off-by: Jian Yu <jian.yu@intel.com>
Change-Id: Ice971aa4b15675c8a5f70f5b32092db69358565e
Reviewed-on: http://review.whamcloud.com/8381
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Wei Liu <wei3.liu@intel.com>
Reviewed-by: Minh Diep <minh.diep@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>