uboot-imx

tools/proftool: fix use-after-free

The read_trace_config() can dereference the line pointer after freeing
it on its error path. Avoid that.

This was found by Coverity Scan.

Signed-off-by: Vincent Stehlé <vincent.stehle@freescale.com>
Cc: Simon Glass <sjg@chromium.org>