test/py: Use the correct fixture name in exception handler

If a BootFail exception is thrown in a test, it is not handled
correctly. Use the correct fixture variable 'ubman_fix' to resolve this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Fixes: d9ed4b75ad ("test/py: Drop u_boot_ prefix on test files")
Reviewed-by: Mattijs Korpershoek <mkorpershoek@kernel.org>

test/py/conftest.py

@@ -514,7 +514,7 @@ def ubman(request):
         handle_exception(ubconfig, ubman_fix, log, err, 'Lab timeout', True)
     except BootFail as err:
         handle_exception(ubconfig, ubman_fix, log, err, 'Boot fail', True,
-                         ubman.get_spawn_output())
+                         ubman_fix.get_spawn_output())
     except Unexpected:
         handle_exception(ubconfig, ubman_fix, log, err, 'Unexpected test output',
                          False)