The function dfs_mlme_mark_dfs_for_freq was introduced as a counterpart of
dfs_mlme_mark_dfs but both implement same functionality. In order to remove
redundancy, remove dfs_mlme_mark_dfs_for_freq. Replace the references to
dfs_mlme_mark_dfs_for_freq with dfs_mlme_mark_dfs.
CRs-Fixed: 2738831
Change-Id: I567861e4491802d73549670dfd30113b1a773d07