cmd: part: Add subcommand to list supported partition tables

Add a subcommand "types" to the part command, which lists the supported
partition table types.

Signed-off-by: Niel Fourie <lusus@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>

test/py/tests/test_part.py

@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2020
+# Niel Fourie, DENX Software Engineering, lusus@denx.de
+
+import pytest
+
+@pytest.mark.buildconfigspec('cmd_part')
+@pytest.mark.buildconfigspec('partitions')
+@pytest.mark.buildconfigspec('efi_partition')
+def test_dm_compat(u_boot_console):
+    """Test that `part types` prints a result which includes `EFI`."""
+    output = u_boot_console.run_command('part types')
+    assert "Supported partition tables:" in output
+    assert "EFI" in output