xfs: convert DM ops to use unsigned char names

dmops uses a signed char for it's namespace event. To be consistent
with the rest of the code, convert them to unsigned char for the
namespace string.

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

diff --cc fs/xfs/xfs_mount.h
Simple merge

diff --cc fs/xfs/xfs_vnodeops.c
Simple merge