supervdsm: remove unused lsblk module

The method getLsBlk was added in commit 6ee565b without any explanation
on why it's needed. I couldn't find any trace of this being ever used.

Change-Id: I850637caab0a91c1e15ed2b1d0533d7f779f6621
Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/30212
Reviewed-by: Dan Kenigsberg <danken@redhat.com>