binman: Don't reset offset/size if image doesn't allow repacking

binman: Don't reset offset/size if image doesn't allow repacking

When an image has the 'allow-repack' property, binman includes the
original offset and size properties from the image description in the
fdtmap. These are later used as the packing constraints when replacing
entries in an image, so other unconstrained entries can be freely
positioned.

Replacing an entry in an image without 'allow-repack' (and therefore the
original offsets) follows the same logic and results in entries being
merely concatenated. Instead, skip resetting the calculated offsets and
sizes to the missing originals for these images so that every entry is
constrained to its existing offset/size.

Add tests that replace an entry with smaller or equal-sized data, in an
image that doesn't allow repacking. Attempting to do so with bigger-size
data is already an error that is already being tested.

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>