Add APIs to fetch the DFS channel parameters such as CAC, NOL and the
channel state to the user application.
struct dfs_cacelem is defined to store all the CAC related information
such as cac start time, cac completed time and the cac timeout.
dfs_cacelems is stored for NUM_5GHZ_CHANS in the dfs pdev object.
dfs_handle_cac_events() API is used to handle CAC related events such
as WLAN_EV_CAC_COMPLETED, WLAN_EV_CAC_RESET and radar during CAC.
CRs-Fixed: 3428828
Change-Id: I82f7aafeb20222d9722bed5a1a8c10b5703ac975
70a7674b32