wifi_mgmt: Extend enumerations to include MAX and UNKNOWN

This is handy to

* Validate the input using MAX
* Return UNKNOWN instead of int "-1"

Signed-off-by: Krishna T <krishna.t@nordicsemi.no>
diff --git a/include/zephyr/net/wifi.h b/include/zephyr/net/wifi.h
index 1063b77..cf55d80 100644
--- a/include/zephyr/net/wifi.h
+++ b/include/zephyr/net/wifi.h
@@ -19,20 +19,29 @@
 	WIFI_SECURITY_TYPE_SAE,
 
 	__WIFI_SECURITY_TYPE_AFTER_LAST,
-	WIFI_SECURITY_TYPE_MAX = __WIFI_SECURITY_TYPE_AFTER_LAST - 1
+	WIFI_SECURITY_TYPE_MAX = __WIFI_SECURITY_TYPE_AFTER_LAST - 1,
+	WIFI_SECURITY_TYPE_UNKNOWN
 };
 
 /* Management frame protection (IEEE 802.11w) options */
 enum wifi_mfp_options {
 	WIFI_MFP_DISABLE = 0,
 	WIFI_MFP_OPTIONAL,
-	WIFI_MFP_REQUIRED
+	WIFI_MFP_REQUIRED,
+
+	__WIFI_MFP_AFTER_LAST,
+	WIFI_MFP_MAX = __WIFI_MFP_AFTER_LAST - 1,
+	WIFI_MFP_UNKNOWN
 };
 
 enum wifi_frequency_bands {
 	WIFI_FREQ_BAND_2_4_GHZ = 0,
 	WIFI_FREQ_BAND_5_GHZ,
-	WIFI_FREQ_BAND_6_GHZ
+	WIFI_FREQ_BAND_6_GHZ,
+
+	__WIFI_FREQ_BAND_AFTER_LAST,
+	WIFI_FREQ_BAND_MAX = __WIFI_FREQ_BAND_AFTER_LAST - 1,
+	WIFI_FREQ_BAND_UNKNOWN
 };
 
 #define WIFI_SSID_MAX_LEN 32