msm: pm: send notification only for SPC and PC

Currently the pm notification is sent for all the low power
modes of each CPU. Generally the subscriber to this notification
expects to be notified for core power collapse. For example
interrupt controller subscribes this notification to save
and restore its context when entering and exit power collapse
respectively. So this is not necessary for shallow power modes
like WFI and Retention.

This change is to send the notification for only standalone
power collapse of each core and idle power collapse of core0.

Change-Id: I39fb6a6bfb47ca49d6ec8df8cad1fd74424140a0
Signed-off-by: Venkat Devarasetty <vdevaras@codeaurora.org>