arm64: topology: Handle CPU topology parsing failure case

When the CPU topology device tree node parsing is failed, the
topology is reset i.e each CPU is marked as its own sibling.
However the newly introduced core_possible_sibling mask is
not updated. This results in an empty core_possible_sibling mask
and scheduler end up preparing a cluster with empty CPUs. This
results in incorrect behavior. Fix this by initializing
core_possible_sibling mask for all CPUs in the reset_cpu_topology()
function. The initializing is done similar to core_sibling_mask i.e
each CPU is its own sibling. Note that we want to do that only
in the error path i.e. reset_cpu_topology() and not in the hotplug
path clear_cpu_topology() since we want to maintain
core_possible_sibling_mask across hotplugs.

Change-Id: I96de8b6a4ef526c9a0589ed4b0fef3313e5fb1e1
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>