Printing a null pointer with %s is flagged as a warning by GCC 9, and
should not be done. Replace the %s with the word "null" itself.
Fixes: 828d51d8fc3e ("bus/fslmc: refactor scan and probe functions")
Cc: stable@dpdk.org
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
33832c1471