xfs_db: print structure padding fields consistently

xfs_db: print structure padding fields consistently

We are very inconsistent about how we print padding fields in on-disk
structures -- sometimes we hide it from printall, sometimes we deviate
from unsigned hex values, etc.  Make this all consistent -- always hide
padding values when printing the whole structure, always print them as
unsigned hex integers when explicitly requested.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
[sandeen: switch to never-print instead of always-print]
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>