scripts: imx-usb-loader: simplify code flow for file size calculations

This change contains several changes that make the code flow easier to
understand (in my eyes at least):

 - Rename max_length to firststage_len
   In some cases the image is loaded in two stages: First the PBL which
   is started after the PBL is loaded completely and then the whole
   image. So the size of the first stage isn't about some maximum.

 - Drop unintuitive total_size variable
   This variable used to be 0 in the one stage case and the filesize
   otherwise. Just use firststage_len for the first stage and use the
   filesize for the second stage (if needed).

 - Don't call the first stage size "fsize" in the debug output.

 - Add offset for second stage to debug output.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.barebox.org/20220617082414.323238-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

0 files changed, 0 insertions, 0 deletions