f2fs: Export the enums in the tracepoints to userspace

The tracepoints that use __print_symbolic() use enums as the value
to convert to strings. Unfortunately, the format files for these
tracepoints show the enum name and not their value. This causes some
userspace tools not to know how to convert __print_symbolic() to
their strings.

Add TRACE_DEFINE_ENUM() macros to export the enums used to userspace
to let those tools know what those enum values are.

Link: http://lkml.kernel.org/r/20150403013802.220157513@goodmis.org
Cc: Namjae Jeon <namjae.jeon@samsung.com>
Cc: Pankaj Kumar <pankaj.km@samsung.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>