MBO: Fix minimum length check on non_pref_chan configuration

The reason detail field in non_pref_chan attribute was removed
from MBO draft v0.0_r25. Also oper_class can be 1 character for
few country codes (e.g., country code-UK, channel number-1). So the
shortest channel configuration is 7 characters.

This was missed in the earlier commit
4a83d4b6861f6627b6b256b8c126547a19409a70 ('MBO: Do not add reason_detail
in non_pref_chan attr (STA)') that took care of other changes related to
removal of the reason detail.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

wpa_supplicant/mbo.c

@@ -277,11 +277,10 @@ int wpas_mbo_update_non_pref_chan(struct wpa_supplicant *wpa_s,
 		   non_pref_chan ? non_pref_chan : "N/A");
 
 	/*
-	 * The shortest channel configuration is 10 characters - commas, 3
-	 * colons, and 4 values that one of them (oper_class) is 2 digits or
-	 * more.
+	 * The shortest channel configuration is 7 characters - 3 colons and
+	 * 4 values.
 	 */
-	if (!non_pref_chan || os_strlen(non_pref_chan) < 10)
+	if (!non_pref_chan || os_strlen(non_pref_chan) < 7)
 		goto update;
 
 	cmd = os_strdup(non_pref_chan);