binman: Add a bit of logging in entries when packing

Use the new logging feature to log information about progress with
packing. This is useful to see how binman is figuring things out.

Also update elf.py to use the same feature.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/elf.py b/tools/binman/elf.py
index 8147b34..af40024 100644
--- a/tools/binman/elf.py
+++ b/tools/binman/elf.py
@@ -17,6 +17,7 @@
 import tempfile
 
 import tools
+import tout
 
 ELF_TOOLS = True
 try:
@@ -25,9 +26,6 @@
 except:  # pragma: no cover
     ELF_TOOLS = False
 
-# This is enabled from control.py
-debug = False
-
 Symbol = namedtuple('Symbol', ['section', 'address', 'size', 'weak'])
 
 # Information about an ELF file:
@@ -143,9 +141,8 @@
                 value = -1
                 pack_string = pack_string.lower()
             value_bytes = struct.pack(pack_string, value)
-            if debug:
-                print('%s:\n   insert %s, offset %x, value %x, length %d' %
-                      (msg, name, offset, value, len(value_bytes)))
+            tout.Debug('%s:\n   insert %s, offset %x, value %x, length %d' %
+                       (msg, name, offset, value, len(value_bytes)))
             entry.data = (entry.data[:offset] + value_bytes +
                         entry.data[offset + sym.size:])