This does 2 things:
- use the correct way to get the size of a disk device or partition
   (from haad@NetBSD.org)
- if given a block device, use the character device instead.
   (from bouyer@NetBSD.org)

From: Adam Hamsik <haad@netbsd.org>
From: Manuel Bouyer <bouyer@netbsd.org>
Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>

-- 
---to satisfy European Law for business letters:
Advanced Micro Devices GmbH
Einsteinring 24, 85689 Dornach b. Muenchen
Geschaeftsfuehrer: Alberto Bozzo, Andrew Bowd
Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632