binman: Use expanduser instead of HOME

There may not be a HOME environment variable, so use the os.expanduser()
function instead.

BUG=b:278256544
TEST=CQ

Change-Id: Id9a69c8cf668c8c5a2e89e52ff38e74153f0e250
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/u-boot/+/4450528
Reviewed-by: Mike Frysinger <vapier@chromium.org>
1 file changed