arm64: smp: Update the topology masks before calling CPU_STARTING notifiers

Currently, the CPU_STARTING notifiers would observe an incorrect sibling
mask since the notifier chain is called before the topology masks are
updated for the new cpu.
Update the topology masks before calling the notifier chain to fix this
problem.

Change-Id: I3f698d777af3bb8e324019619b4c1c4de85e7b2c
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>