Try to set PMK only with key mgmt offload support in the driver
Previously, it was possible for the set_key() handler to be used with
WPA_ALG_PMK even if the driver did not indicate support for key
management offload. While this is not really supposed to result in any
difference, it makes the debug logs somewhat confusing. Avoid that by
using driver capability flag for key management offload as an additional
condition for setting the PMK.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>