Check hostapd current_mode before dereferencing it in additional places

Check hostapd current_mode before dereferencing it in additional places

While most places using this should be for cases where the hw_features
functionality is required, there seem to be some paths that are getting
exposed in new OWE related operations where that might not be the case.
Add explicit NULL pointer checks to avoid dereferencing the pointer if
it is not set when operating with driver wrappers that do not provide
sufficient information.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>