test: py: Extend fpga test with fit image with external data

Images are created
mkimage -f fit.its -E  download-fit-external.ub

and test expects these entries.

env__fpga_under_test = {
    ...
    "mkimage_fit_external": download-fit-external.ub",
    "mkimage_fit_external_size": xxxxx,
    ...
}

Test download file and loads it to fpga.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/test/py/tests/test_fpga.py b/test/py/tests/test_fpga.py
index 798f6ee..e3bb7b4 100644
--- a/test/py/tests/test_fpga.py
+++ b/test/py/tests/test_fpga.py
@@ -357,6 +357,19 @@
 @pytest.mark.buildconfigspec('cmd_fpga_loadmk')
 @pytest.mark.buildconfigspec('fit')
 @pytest.mark.buildconfigspec('cmd_echo')
+def test_fpga_loadmk_fit_external(u_boot_console):
+    f, dev, addr, bit, bit_size = load_file_from_var(u_boot_console, 'mkimage_fit_external')
+
+    u_boot_console.run_command('imi %x' % (addr))
+
+    expected_text = 'FPGA loaded successfully'
+    output = u_boot_console.run_command('fpga loadmk %x %x:fpga && echo %s' % (dev, addr, expected_text))
+    assert expected_text in output
+
+@pytest.mark.buildconfigspec('cmd_fpga')
+@pytest.mark.buildconfigspec('cmd_fpga_loadmk')
+@pytest.mark.buildconfigspec('fit')
+@pytest.mark.buildconfigspec('cmd_echo')
 def test_fpga_loadmk_fit(u_boot_console):
     f, dev, addr, bit, bit_size = load_file_from_var(u_boot_console, 'mkimage_fit')