binman: Support replacing data in a cbfs

At present binman cannot replace data within a CBFS since it does not
allow rewriting of the files in that CBFS. Implement this by using the
new WriteData() method to handle the case.

Add a header to compressed data so that the amount of compressed data can
be determined without reference to the size of the containing entry. This
allows the entry to be larger that the contents, without causing errors in
decompression. This is necessary to cope with a compressed device tree
being updated in such a way that it shrinks after the entry size is
already set (an obscure case). It is not used with CBFS since it has its
own metadata for this. Increase the number of passes allowed to resolve
the position of entries, to handle this case.

Add a test for this new logic.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/binman/control.py

@@ -311,7 +311,7 @@ def ProcessImage(image, update_fdt, write_map, get_contents=True,
     # since changing an offset from 0x100 to 0x104 (for example) can
     # alter the compressed size of the device tree. So we need a
     # third pass for this.
-    passes = 3
+    passes = 5
     for pack_pass in range(passes):
         try:
             image.PackEntries()