qca-wifi: Use node's subchannel count instead of hardcoded values

While finding the CAC status of a channel, the tree root's
subchannel count is hardcoded to 8 (subchannel count for 160MHz
channel) after the Pine ADFS changes.

In certain RDPs, the maximum bandwidth of a channel is only 80MHz
and in those cases, the preCAC tree roots are 80MHz channels. Now
while checking if a channel is CAC done, the number of CAC done
subchannels should be equal to the number of subchannels in the
corresponding tree node. But since the tree root's subchannel count
is not calculated but is hardcoded to 160MHz, it fails in these
RDPs (with 80MHz channels) and a channel is never considered CAC
done.

To avoid this issue, use the tree root's n_valid_subchs value
as the number of subchannels instead of hardcoding it to 8.

CRs-Fixed: 2684954
Change-Id: I85e5ea6e4bb71dc9b1ba951b8e227f487e3d11f6

umac/dfs/core/src/misc/dfs_zero_cac.c

@@ -509,7 +509,7 @@ dfs_find_cac_status_for_chan_for_freq(struct dfs_precac_entry *precac_entry,
 				      uint16_t chan_freq)
 {
 	struct precac_tree_node *node = precac_entry->tree_root;
-	uint8_t n_cur_lvl_subchs = N_SUBCHANS_FOR_160BW;
+	uint8_t n_cur_lvl_subchs = node->n_valid_subchs;
 
 	while (node) {
 		if (node->ch_freq == chan_freq)