spl: fit: Remove useless loop in spl_fit_get_image_name()

When a desired configuration is not found, conf_node will have a
negative value. Thus the for loop will start at the root "/" node of
the image, print the "/description" property, and stop.

It appears the intent of the loop was to print the names of the
subnodes under "/configurations". We would need the offset to the
"/configurations" node, which is abstracted by fit_find_config_node().

This change agrees that abstracting the node offset is the correct
design, and we shouldn't be parsing the configurations manually. Thus
the loop in spl_fit_get_image_name() is useless. Remove it.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>