Clean up test function pk_parse_key

- remove incorrect compile-time dependency (the individual cases already have
  correct run-time dependency information)
- remove unused argument
- remove unused stack buffer
- remove useless code block
diff --git a/tests/suites/test_suite_pkparse.function b/tests/suites/test_suite_pkparse.function
index 3eb0397..4650d33 100644
--- a/tests/suites/test_suite_pkparse.function
+++ b/tests/suites/test_suite_pkparse.function
@@ -113,23 +113,14 @@
 }
 /* END_CASE */
 
-/* BEGIN_CASE depends_on:MBEDTLS_RSA_C */
-void pk_parse_key( data_t * buf, char * result_str, int result )
+/* BEGIN_CASE */
+void pk_parse_key( data_t * buf, int result )
 {
     mbedtls_pk_context pk;
-    unsigned char output[2000];
-    ((void) result_str);
 
     mbedtls_pk_init( &pk );
 
-    memset( output, 0, 2000 );
-
-
-    TEST_ASSERT( mbedtls_pk_parse_key( &pk, buf->x, buf->len, NULL, 0 ) == ( result ) );
-    if( ( result ) == 0 )
-    {
-        TEST_ASSERT( 1 );
-    }
+    TEST_ASSERT( mbedtls_pk_parse_key( &pk, buf->x, buf->len, NULL, 0 ) == result );
 
 exit:
     mbedtls_pk_free( &pk );