binman: Rename Entry property to 'section'

Entries are now passed a Section object rather than an Image. Rename this
property to avoid confusion.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/ftest.py b/tools/binman/ftest.py
index 4a95a9c..96a5535 100644
--- a/tools/binman/ftest.py
+++ b/tools/binman/ftest.py
@@ -800,7 +800,7 @@
             self._DoReadFile('40_x86_ucode_not_in_image.dts', True)
         self.assertIn("Node '/binman/u-boot-with-ucode-ptr': Microcode "
                 "pointer _dt_ucode_base_size at fffffe14 is outside the "
-                "image ranging from 00000000 to 0000002e", str(e.exception))
+                "section ranging from 00000000 to 0000002e", str(e.exception))
 
     def testWithoutMicrocode(self):
         """Test that we can cope with an image without microcode (e.g. qemu)"""