tracing: Prefer kcalloc over kzalloc with multiply

Use kcalloc for allocating an array instead of kzalloc with multiply,
as that is what kcalloc is used for.
Found with checkpatch.

Link: http://lkml.kernel.org/r/1433835155-6894-2-git-send-email-gilf@ezchip.com



Signed-off-by: Gil Fruchter <gilf@ezchip.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>