icnss: Do not clear SHUTDOWN_DONE flag until reinit is done

In case of SSR/PDR, when FW comes up, platform driver receives
FW_READY indication. As part of FW_READY, platform driver calls
shutdown and reinit ops of host driver.
Clear SHUTDOWN_DONE flag at right place so that if reinit is not
called SSR/PDR because of FW again went down between calling driver
shutdown and reinit then next time directly call reinit and avoid
calling shutdown.

Change-Id: I2a8bd77ab47d5008b705010f09084cbfebc4d06e
Signed-off-by: Naman Padhiar <npadhiar@codeaurora.org>