Btrfs/tracepoint: fix to report right flags for ordered extent

We use set_bit() to assign ordered extent's flags, but in the related
tracepoint we don't do the same thing, which makes the trace output
not to parse flags correctly.

Also, since the flags are bits stuff, we change to use __print_flags with
a 'delim' instead of __print_symbolic.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>