test/py: Handle testing with the sandbox_spl board

This board can sometimes be used for tests. Handle it the same way as
sandbox.

Note: I plan to drop the sandbox_spl board at some point and merge its
features into sandbox. So this commit may not be necessary.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/py/conftest.py b/test/py/conftest.py
index 449f98b..050f6e4 100644
--- a/test/py/conftest.py
+++ b/test/py/conftest.py
@@ -192,7 +192,7 @@
     for v in env_vars:
         os.environ['U_BOOT_' + v.upper()] = getattr(ubconfig, v)
 
-    if board_type == 'sandbox':
+    if board_type.startswith('sandbox'):
         import u_boot_console_sandbox
         console = u_boot_console_sandbox.ConsoleSandbox(log, ubconfig)
     else: