msm: hotplug: Add suspend_defer_time

* After discussions with @franciscofranco, let's use more
  suspend/resume helper LCD notifier, since now we can
  control suspend delay.
* As name suggest, suspend takes are place after some
  delay when screen is turned off. Default - 10 seconds.
* If user resumes device before suspend_defer_time seconds,
  all cores go online as before but suspend work is
  canceled and rescheduling is not done.
* If screen is turned off and suspend_defer_time is exceeded,
  all sibling cores shut down as before. While resuming,
  all cores go online for downlock duration and hotplug
  resumes working.

* Restructure msm_hotplug_mutex and suspended variables.

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>