uboot-imx

test: Fix FIT test to pass again

A recent change adjusted a test string so that the test no-longer passes.
Fix it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reported-by: Heiko Schocher <hs@denx.de>
Fixes: b28c5fcc (test-fit.py: Minor grammar/spelling/clarification tweaks)