This re-introduces the orignal patch which shutdowns WLAN in system
suspend prepare.
Orignal patch Id1f5172a7fc1792c83c8c1c20127de815f7e4980 is reverted by
Ic82db9dc0ca9d6686df99926335af27abc61cdb5 for deadlock issue.
However, deadlock between cnss_pm_notify and unregister_pm_notifier is
not caused by Id1f5172a7fc1792c83c8c1c20127de815f7e4980. So restore it
and add flag to enable/disable feature shutdown wlan in system suspend.
Deadlock issue is caused by "up_write(&cnss_pm_sem) is invoked before
down_write(&cnss_pm_sem) in function cnss_pm_notify". The issue can be
fixed by changes I533c373b85f554fbcceb562d9f56c6b88e5155bb and
I7768fdbeb1fa8cd6ef3b260eb0aafb231aeed324.
Change-Id: I25e4398a8d3b1a52cf7bc554af74d123ec797c6e
CRs-Fixed: 3287742
85f34a3bb9