wl12xx: FM WLAN coexistence

Add support to FM WLAN coexistence (STA only).  Some WiFi harmonics
may interfere with FM operation, to avoid this problem special
coexistence techniques are activated around some FM frequencies.

Signed-off-by: Shahar Levi <shahar_levi@ti.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>