doc: Remove duplicate description for -t

Signed-off-by: Reiner Herrmann <reiner@reiner-h.de>

wpa_supplicant/doc/docbook/wpa_supplicant.sgml

@@ -376,13 +376,6 @@
 	</listitem>
       </varlistentry>
 
-      <varlistentry>
-	<term>-t</term>
-	<listitem>
-	  <para>Include timestamp in debug messages.</para>
-	</listitem>
-      </varlistentry>
-
       <varlistentry>
 	<term>-h</term>
 	<listitem>