mt76x2: dfs: add sw pattern detector

Add sw DFS pattern detector support for mt76x2 based devices.
Dfs pattern supported:
- short pulse radar patterns
- staggered radar patterns

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>