icnss: Avoid qmi exchange when fw is down

Currently wlan Host driver call exported API's which
invoke qmi exchanges irrespective of the firmware status
which leads to QMI timeouts.
To address this issue avoid sending qmi request to
firmware when firmware is down.

CRs-Fixed: 2175302
Change-Id: Ie5e340cebf7ee7f6143472e7dca0dfd9600d1b7d
Signed-off-by: Anurag Chouhan <achouhan@codeaurora.org>