selftests: livepatch: use canonical ftrace path

Since v4.1 kernel, a new interface for ftrace called "tracefs" was
introduced, which is usually mounted in /sys/kernel/tracing. Therefore,
tracing files can now be accessed via either the legacy path
/sys/kernel/debug/tracing or the newer path /sys/kernel/tracing.

Signed-off-by: Fushuai Wang <[e-mail]>
Reviewed-by: Petr Mladek <[e-mail]>
Tested-by: Petr Mladek <[e-mail]>
Signed-off-by: Petr Mladek <[e-mail]>

tools/testing/selftests/livepatch/functions.sh

···
 SYSFS_KLP_DIR="$SYSFS_KERNEL_DIR/livepatch"
 SYSFS_DEBUG_DIR="$SYSFS_KERNEL_DIR/debug"
 SYSFS_KPROBES_DIR="$SYSFS_DEBUG_DIR/kprobes"
-SYSFS_TRACING_DIR="$SYSFS_DEBUG_DIR/tracing"
+if [[ -e /sys/kernel/tracing/trace ]]; then
+	SYSFS_TRACING_DIR="$SYSFS_KERNEL_DIR/tracing"
+else
+	SYSFS_TRACING_DIR="$SYSFS_DEBUG_DIR/tracing"
+fi
 
 # Kselftest framework requirement - SKIP code is 4
 ksft_skip=4