tools lib traceevent: Fix signature of create_arg_item()

The @type should be a type of enum event_type not enum filter_arg_type.

This fixes following warning:

 $ make
  COMPILE FPIC           parse-events.o
  COMPILE FPIC           parse-filter.o
/home/namhyung/project/trace-cmd/parse-filter.c: In function ‘create_arg_item’:
/home/namhyung/project/trace-cmd/parse-filter.c:343:9: warning: comparison between ‘enum filter_arg_type’ and ‘enum event_type’ [-Wenum-compare]
/home/namhyung/project/trace-cmd/parse-filter.c:339:2: warning: case value ‘8’ not in enumerated type ‘enum filter_arg_type’ [-Wswitch]
  BUILD STATIC LIB       libparsevent.a
  BUILD STATIC LIB       libtracecmd.a
  BUILD                  trace-cmd
/usr/bin/make -C /home/namhyung/project/trace-cmd/Documentation all
make[1]: Nothing to be done for `all'.
Note: to build the gui, type "make gui"

Cc: Borislav Petkov <bp@alien8.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1337740619-27925-20-git-send-email-namhyung.kim@lge.com
Signed-off-by: Namhyung Kim <namhyung.kim@lge.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>