SSD pool creation issue

Closes-Bug: #1392622
Issue: When more than one disk is present in the SSD pool,
    the crushmap modification code aborts.
Fix: The dictionary index for the osd weight variable was
    wrong. The index was pointing to a wrong field of
    ('hostname', 'count') instead of ('hostname-poolname', 'count').
    Fixed the above issue.
Test: Verified with more than one SSD disk in the SSD pool

Change-Id: I093a8e4b46405160533f769ecc2f71d0efe0462a