Revert "topology: Add snapshot of possible sibling cpu mask changes"

Cpu possible sibling cpu mask is only used by WALT for its cluster
population. And WALT is directly getting the cpu possible sibling mask.

So remove this unused cpu mask support by reverting commit:
'6df025a0("topology: Add snapshot of possible sibling
cpu mask changes")'.

Change-Id: If65842a37cad95e8b52425a1397d12c32a95dc1e
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>