wifi: Inform framework HAPD_IFACE_DISABLED when AP iface unavailable

This change adds callback to inform framework AP interface
HAPD_IFACE_DISABLED when driver event INTERFACE_UNAVAILABLE.

Bug: 197292709
Test: Local build & manual test disable/enable Wi-Fi
Change-Id: I8b6bad1a6444737e7cdbaaedb1eb0c85a86eb240
diff --git a/src/ap/drv_callbacks.c b/src/ap/drv_callbacks.c
index 53082f5..de51772 100644
--- a/src/ap/drv_callbacks.c
+++ b/src/ap/drv_callbacks.c
@@ -1673,6 +1673,9 @@
 		hostapd_switch_channel_fallback(hapd->iface,
 						&hapd->cs_freq_params);
 	}
+
+	// inform framework that interface is unavailable
+	hostapd_disable_iface(hapd->iface);
 }