memfd_test: Add missing argument to printf()

Add a missing path argument buf to printf()

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>

diff --cc tools/testing/selftests/memfd/memfd_test.c
Simple merge