trace: Handle empty and oversized packets

Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Change-Id: I24f5d5973b47652ff1357756d9a01b85c41c1682
Reviewed-on: https://review.coreboot.org/c/em100/+/48587
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
1 file changed