test: let use gdbserver for all sandbox targets

Enable usage of gdbserver for all sandbox targets (sandbox,
sandbox_flattree etc.).

Signed-off-by: Igor Opaniuk <igor.opaniuk@linaro.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/test/py/conftest.py b/test/py/conftest.py
index 5c658b8..e40cbf0 100644
--- a/test/py/conftest.py
+++ b/test/py/conftest.py
@@ -117,8 +117,8 @@
     mkdir_p(persistent_data_dir)
 
     gdbserver = config.getoption('gdbserver')
-    if gdbserver and board_type != 'sandbox':
-        raise Exception('--gdbserver only supported with sandbox')
+    if gdbserver and not board_type.startswith('sandbox'):
+        raise Exception('--gdbserver only supported with sandbox targets')
 
     import multiplexed_log
     log = multiplexed_log.Logfile(result_dir + '/test-log.html')