msm: pm: Send L2 flush flag for last core during hotplug

In a multi-cluster system, the last core in the cluster would power
collapse the L2 logic as well. The L2 flag has to be set accordingly to
ensure L2 flush flag is set accordingly.

Change-Id:I84fd71de57040c34961dc3a0b3fc4a4a514bc18f
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>