disklabel_sun_to_bsd() will nicely set the disk size if it is zero, but it is

disklabel_sun_to_bsd() will nicely set the disk size if it is zero, but it is
usually invoked after initdisklabel() which proactively changes a zero disk
size to MAXDISKSIZE, causing this test to fail.

Allow for MAXDISKSIZE too in that test. This makes spoofed disklabels of SMD
disks have a proper `c' slice size.

luna88k disklabel_om_to_bsd() is modified accordingly, to keep diffability,
even though luna88k can't - to the best of my knowledge - sport SMD disk
controllers.

ok deraadt@ krw@