tools lib traceevent: Update printk formats when entered

Instead of cropping off the '"' and '\n"' from a printk format every
time it is referenced, do it when it's added. This makes it easier to
reference a printk_map and should speed things up a little.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20131101215500.495619312@goodmis.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>