LVM: Activate source snap LV when cloning from volume

Similar to the change made in:
01a2199 LVM: Activate source LV before cloning from it

Previous change only fixed this issue for clone-from-snapshot.

This activates the source snapshot LV when cloning from volume
as well, fixing the problem where cloning fails due to inability
to open the source LV device.

Change-Id: If48be8516fd71738cb83a91683c33d02f227b9d6
Related-Bug: 1252423
Closes-Bug: 1260786
Merge "LVM: Activate source snap LV when cloning from volume"