test: Add DEBUG output option to test-fit.py

Sometimes it is useful to see the output from U-Boot, so add an option to
make this easier.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/image/test-fit.py b/test/image/test-fit.py
index 0eb424d..e9e756a 100755
--- a/test/image/test-fit.py
+++ b/test/image/test-fit.py
@@ -20,6 +20,9 @@
 import sys
 import tempfile
 
+# Enable printing of all U-Boot output
+DEBUG = True
+
 # The 'command' library in patman is convenient for running commands
 base_path = os.path.dirname(sys.argv[0])
 patman = os.path.join(base_path, '../../tools/patman')
@@ -103,6 +106,10 @@
 reset
 '''
 
+def debug_stdout(stdout):
+    if DEBUG:
+        print stdout
+
 def make_fname(leaf):
     """Make a temporary filename
 
@@ -328,6 +335,7 @@
     # We could perhaps reduce duplication with some loss of readability
     set_test('Kernel load')
     stdout = command.Output(u_boot, '-d', control_dtb, '-c', cmd)
+    debug_stdout(stdout)
     if read_file(kernel) != read_file(kernel_out):
         fail('Kernel not loaded', stdout)
     if read_file(control_dtb) == read_file(fdt_out):
@@ -352,6 +360,7 @@
     params['fdt_load'] = 'load = <%#x>;' % params['fdt_addr']
     fit = make_fit(mkimage, params)
     stdout = command.Output(u_boot, '-d', control_dtb, '-c', cmd)
+    debug_stdout(stdout)
     if read_file(kernel) != read_file(kernel_out):
         fail('Kernel not loaded', stdout)
     if read_file(control_dtb) != read_file(fdt_out):
@@ -365,6 +374,7 @@
     params['ramdisk_load'] = 'load = <%#x>;' % params['ramdisk_addr']
     fit = make_fit(mkimage, params)
     stdout = command.Output(u_boot, '-d', control_dtb, '-c', cmd)
+    debug_stdout(stdout)
     if read_file(ramdisk) != read_file(ramdisk_out):
         fail('Ramdisk not loaded', stdout)