tracing: Remove duplicate latency_fsnotify() stub

tracing: Remove duplicate latency_fsnotify() stub

When the SNAPSHOT is defined but FSNOTIFY is not the latency_fsnotify()
function is turned into a static inline stub. But this stub was defined in
both trace.h and trace_snapshot.c causing a error in build when
CONFIG_SNAPSHOT is defined but FSNOTIFY is not. The stub is not needed in
trace_snapshot.c as it will be defined in trace.h, remove it from the C
file.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20260330205859.24c0aae3@gandalf.local.home
Fixes: bade44fe5462 ("tracing: Move snapshot code out of trace.c and into trace_snapshot.c")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202603310604.lGE9LDBK-lkp@intel.com/
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>