xfs: do not use emums for flags used in tracing

The tracing code can't print flags defined as enums.  Most flags that
we want to print are defines as macros already, but move the few remaining
ones over to make the trace output more useful.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>