xfs: trace ATTR flags in xattr tracepoints

This will trace i.e. the ATTR_SECURE/ATTR_CREATE/ATTR_REPLACE
flags as well as the OP_FLAGS.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>