qca-wifi: Add frequency-based APIs in ADFS to communicate with DFS module

The IEEE channel numbers in the 6GHz band overlap with the IEEE channel
numbers in 2.4GHz, 4.9GHz (e.g. Channel number 1) and 5GHz
(e.g. Channel number 149). Currently many APIs in Agile DFS (ADFS),
have channel number as a parameter. This leads to the channel number
collision. To overcome this, new APIs with channel center frequency
(in units of megahertz or MHz) as a parameter are created, as
channel center frequency is unique for 2.4 GHz, 4.9 GHz, 5GHz,
and 6GHz channels.

Each new API performs the same function as its old counterpart.
For example dfs_find_cac_status_for_chan() and
dfs_find_cac_status_for_chan_for_freq() perform the same operation. The
difference in the latter, is that the channel center frequency is given
as an input parameter instead of IEEE channel number, and the function
body is modified to suit channel center frequency.
The new channel frequency based APIs are placed under the macro
"CONFIG_CHAN_FREQ_API" and the existing channel number based APIs are
placed under the macro "CONFIG_CHAN_NUM_API". The APIs under the macro
CONFIG_CHAN_NUM_API will be removed, when when all the references to
the APIs are removed.

CRs-Fixed: 2526360
Change-Id: Icff94f518af3621b039f059f1409106a5639ed8b