uboot-imx

tools: dumpimage: Simplify internal logic

There are 3 supported modes of operation:

1) Show version
2) List image contents
3) Extract image component

Option (1) terminates early, so only options (2) and (3) remain. Remove
redundant check for these modes.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>