binman: Allow writing a map file when something goes wrong

binman: Allow writing a map file when something goes wrong

When we get a problem like overlapping regions it is sometimes hard to
figure what what is going on. At present we don't write the map file in
this case. However the file does provide useful information.

Catch any packing errors and write a map file (if enabled with -m) to aid
debugging.

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