eina-test: Fix unchecked return value

Coverity CID1401015 complains about an unchecked return value here, so
let's check that fread actually succeeded (return > 0).

Fixes CID1401015

@fix

src/tests/eina/eina_test_simple_xml_parser.c

@@ -237,7 +237,7 @@ EFL_START_TEST(eina_simple_xml_parser_parse_with_custom_callback)
 
             if (buf)
               {
-                if (fread(buf, 1, sz, f))
+                if (fread(buf, 1, sz, f) > 0)
                   {
                     int parse_current_state = simple_xml_parser_current_state_begin;
                     eina_simple_xml_parse(buf,