Before sending Spectral stop WMI to FW check whether Spectral
scan is in progress. When all vdevs are in down state host driver
will send a stop Spectral scan command to FW. In that scenario there
is a possibility that stop Spectral scan WMI message may go to FW
even though Spectral scan is not active. To prevent this we add a check
in stop Spectral scan routine to send WMI message only if
scan is in progress.
CRs-Fixed: 2424020
Change-Id: I2119935759c40f62df75574b6a29174973f2703f
79a5edccee