cnss2: Skip PCIe link suspend if link has already been suspended

If wlan is loaded but without any activity for a period, wlan will
enter into shutdown status, which will suspend PCIe link.

Then if wlan unloading is issued, unloading process should skip
link suspend.

Change-Id: Id366401c656102cac5c5432a5b9a9a77e429cbbc
Signed-off-by: Kai Liu <kaliu@codeaurora.org>