Fix QPermission documentation for accessing typed permissions

The documentation suggested to use a non-existing data() function.
Fix it to mention the actual QPermission::value() method.

Pick-to: 6.5
Change-Id: I870021ef5a04edc26553d8b0376da007687b2f05
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

src/corelib/kernel/qpermissions.cpp

@@ -198,7 +198,7 @@ Q_LOGGING_CATEGORY(lcPermissions, "qt.permissions", QtWarningMsg);
     \endcode
 
     To inspect the properties of the original, typed permission,
-    use the data() function:
+    use the \l {QPermission::}{value()} function:
 
     \code
     QLocationPermission locationPermission;