uboot-imx

Fix hash verification

Fix issue in parse_verify_sum() which swaps handling of env-var and *address.
Move hash_command() argc check earlier.
Cosmetic change on do_hash() variable declaration.
Improved help message for "hash" command.

Signed-off-by: Nikolay Dimitrov <picmaster@mail.bg>
Reviewed-by: Simon Glass <sjg@chromium.org>