cnss2: Return proper error code for nonsupported devices

Platform driver only forces FW assert for supported devices.
Return proper error code for nonsupported devices so that WLAN
host driver can handle properly.

Change-Id: Iaf88f64564b14425404404db6a7789a7913db74f
CRs-fixed: 2059087
Signed-off-by: Yue Ma <yuem@codeaurora.org>