tracing: Use ARRAY_SIZE() macro instead of open coding it

tracing: Use ARRAY_SIZE() macro instead of open coding it

It is useless to re-invent the ARRAY_SIZE macro so let's use it instead
of DATA_CNT.

Found with Coccinelle with the following semantic patch:
@r depends on (org || report)@
type T;
T[] E;
position p;
@@
(
 (sizeof(E)@p /sizeof(*E))
|
 (sizeof(E)@p /sizeof(E[...]))
|
 (sizeof(E)@p /sizeof(T))
)

Link: http://lkml.kernel.org/r/20171016012250.26453-1-jeremy.lefaure@lse.epita.fr
Signed-off-by: Jérémy Lefaure <jeremy.lefaure@lse.epita.fr>
[ Removed useless include of kernel.h ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>