sandbox: Stop printing platdata at the start of SPL

Currently we have code which prints out platform data at the start of SPL.
Now that we have tests for dtoc this is probably not necessary. Drop it.
Update test_ofplatdata to check for empty output since it is useful to
check that sandbox_spl works as expected.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/py/tests/test_ofplatdata.py b/test/py/tests/test_ofplatdata.py
index 457c405..0660ce4 100644
--- a/test/py/tests/test_ofplatdata.py
+++ b/test/py/tests/test_ofplatdata.py
@@ -4,35 +4,7 @@
 
 import pytest
 
-OF_PLATDATA_OUTPUT = '''
-of-platdata probe:
-bool 1
-byte 05
-bytearray 06 00 00
-int 1
-intarray 2 3 4 0
-longbytearray 09 0a 0b 0c 0d 0e 0f 10 11
-string message
-stringarray "multi-word" "message" ""
-of-platdata probe:
-bool 0
-byte 08
-bytearray 01 23 34
-int 3
-intarray 5 0 0 0
-longbytearray 09 00 00 00 00 00 00 00 00
-string message2
-stringarray "another" "multi-word" "message"
-of-platdata probe:
-bool 0
-byte 00
-bytearray 00 00 00
-int 0
-intarray 0 0 0 0
-longbytearray 00 00 00 00 00 00 00 00 00
-string <NULL>
-stringarray "one" "" ""
-'''
+OF_PLATDATA_OUTPUT = ''
 
 @pytest.mark.buildconfigspec('spl_of_platdata')
 def test_ofplatdata(u_boot_console):