xpass: fix function names (#4326)

Author: remicollet

reference/xpass/functions/crypt-checksalt.xml

@@ -10,7 +10,7 @@
  <refsect1 role="description">
   &reftitle.description;
   <methodsynopsis>
-   <type class="union"><type>string</type><type>null</type></type><methodname>crypt_preferred_method</methodname>
+   <type class="union"><type>string</type><type>null</type></type><methodname>crypt_checksalt</methodname>
    <methodparam><type>string</type><parameter>salt</parameter></methodparam>
   </methodsynopsis>
   <para>

reference/xpass/functions/crypt-gensalt.xml

@@ -10,7 +10,7 @@
  <refsect1 role="description">
   &reftitle.description;
   <methodsynopsis>
-   <type class="union"><type>string</type><type>null</type></type><methodname>crypt_preferred_method</methodname>
+   <type class="union"><type>string</type><type>null</type></type><methodname>crypt_gensalt</methodname>
    <methodparam choice="opt"><type>string</type><parameter>prefix</parameter><initializer>&null;</initializer></methodparam>
    <methodparam choice="opt"><type>int</type><parameter>count</parameter><initializer>0</initializer></methodparam>
   </methodsynopsis>