power_mgmt: Rename _sys_soc_resume notification disabling API

The API to disable _sys_soc_resume notification is currently
called _sys_soc_disable_wake_event_notification. This is
misleading because it is possible that the ISR from which
_sys_soc_resume is called could be from a different interrupt
with higher priority that happened before interrupts were
enabled. More accurately, it is a notification of exit from
kernel idling after pm operations.

Jira: ZEP-1271
Change-Id: I83747f2cacac1bc17f135d12f4aa4478970fc02d
Signed-off-by: Ramesh Thomas <ramesh.thomas@intel.com>