binman: Move to absolute imports

At present binman sets the python path on startup so that it can access
the libraries it needs. If we convert to use absolute imports this is not
necessary.

Move binman to use absolute imports. This enables removable of the path
adjusting in Entry also.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/image_test.py b/tools/binman/image_test.py
index 10f85d1..f85c3c5 100644
--- a/tools/binman/image_test.py
+++ b/tools/binman/image_test.py
@@ -7,7 +7,7 @@
 import unittest
 
 from image import Image
-from test_util import capture_sys_output
+from patman.test_util import capture_sys_output
 
 class TestImage(unittest.TestCase):
     def testInvalidFormat(self):