icnss: Synchronize idle shutdown and restart

If WLAN interface is not brought up for certain amount of time
after it is created, idle shutdown will happen to power off WLAN
device. Idle restart will happen to power up WLAN device if WLAN
is needed by user again. Add the support in platform driver.

Change-Id: I63e85c7de20536fc4146e05146e72537095025e5
Signed-off-by: Naman Padhiar <npadhiar@codeaurora.org>