tracing/histogram: Fix a potential memory leak for kstrdup()
This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v5.4.176 by commit 8a8878ebb596281f50fc0b9a6e1f23f0d7f154e8, it was introduced in version v5.4.19 by commit 38b67e60b6b582e81f9db1b2e7176cbbfbd3e574. For more details please see the references link.