xfs: rename i_disk_size fields in ftrace output

Whenever we record i_disk_size (i.e. the ondisk file size), use the
"disize" tag and hexadecimal format consistently.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>