test: py: Add cmd_echo dependency

There is missing dependency on echo command. Mark tests which requires
echo.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>

test/py/tests/test_shell_basics.py

@@ -4,6 +4,10 @@
 
 # Test basic shell functionality, such as commands separate by semi-colons.
 
+import pytest
+
+pytestmark = pytest.mark.buildconfigspec('cmd_echo')
+
 def test_shell_execute(u_boot_console):
     """Test any shell command."""