ACS: Use frequency params in ACS (offload) completed event interface

ACS: Use frequency params in ACS (offload) completed event interface

Replace channel fields with frequency fields in ACS completed event
interface from the driver layer. Use
QCA_WLAN_VENDOR_ATTR_ACS_PRIMARY_FREQUENCY and
QCA_WLAN_VENDOR_ATTR_ACS_SECONDARY_FREQUENCY attributes if the driver
includes them in the QCA_NL80211_VENDOR_SUBCMD_DO_ACS event, otherwise
use QCA_WLAN_VENDOR_ATTR_ACS_PRIMARY_CHANNEL and
QCA_WLAN_VENDOR_ATTR_ACS_SECONDARY_CHANNEL attributes to maintain
backwards compatibility with old drivers.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>