uboot-imx

fdtgrep: Fix logic of free() in do_fdtgrep()

This loop never actually exits, but the way the code is written this is
not obvious. Add an explicit error check.

Reported-by: Coverity (CID: 131280)
Signed-off-by: Simon Glass <sjg@chromium.org>
[trini: Add explicit init of region to NULL per LLVM warning]
Signed-off-by: Tom Rini <trini@konsulko.com>