tools lib traceevent: Show contents (in hex) of data of unrecognized type records

tools lib traceevent: Show contents (in hex) of data of unrecognized type records

When a record has an unrecognized type, an error message is reported,
but it would also be helpful to see the contents of that record. At
least show what it is in hex, instead of just showing a blank line.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20180112004822.542204577@goodmis.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>