tracing: Remove definition of DEBUG in trace_mmiotrace.c

Defining DEBUG should only be done in development.
So remove DEBUG.

Link: https://lkml.kernel.org/r/20210115153348.131791-1-trix@redhat.com



Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>