tracing: Restore accidentally removed SPDX tag

Restore the SPDX tag that was accidentally dropped.

Fixes: 7e4b6c94 ("tracing: add more symbols to whitelist")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Vincent Donnefort <vdonnefort@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://patch.msgid.link/20260317194252.1890568-1-maz@kernel.org


Signed-off-by: Marc Zyngier <maz@kernel.org>