EX-2659 tests: allow multiple MDTs in sanity-lipe.sh

EX-2659 tests: allow multiple MDTs in sanity-lipe.sh

This patch improves sanity-lipe.sh to support
multiple MDTs.

Test-Parameters: trivial testlist=sanity-lipe
Test-Parameters: trivial testlist=sanity-lipe facet=mds1
Test-Parameters: trivial mdscount=2 mdtcount=4 \
testlist=sanity-lipe

Test-Parameters: trivial env=LIPE_FIND=lipe_find2 \
testlist=sanity-lipe
Test-Parameters: trivial env=LIPE_FIND=lipe_find2 \
testlist=sanity-lipe facet=mds1
Test-Parameters: trivial env=LIPE_FIND=lipe_find2 \
mdscount=2 mdtcount=4 testlist=sanity-lipe

Change-Id: I9db6f01e810e8c40e419dcfad409741a3334687c
Signed-off-by: Jian Yu <yujian@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/44588
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Nunez <jnunez@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: John L. Hammond <jhammond@whamcloud.com>