Commit f7a354d("Generate image headers from their PNG source, while still
including them in dist tarball") provides a default PNG files removing the image
generation in build time. This commit overwrites the default PNG with one
customized by Digi.
https://jira.digi.com/browse/DEL-7508
Signed-off-by: Arturo Buzarra <arturo.buzarra@digi.com>