tracing: Replace kzalloc with kcalloc

Replace kzalloc() function with its 2-factor argument form, kcalloc().

This patch replaces cases of:

	kzalloc(a * b, gfp)

with:
	kcalloc(a, b, gfp)

This code was detected with the help of Coccinelle.

Link: http://lkml.kernel.org/r/20190115043408.GA23456@embeddedor



Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>