[SUNVDC]: Use slice 0xff on VD_DISK_TYPE_DISK.

[SUNVDC]: Use slice 0xff on VD_DISK_TYPE_DISK.

While debugging issues with the VDS server I made the
driver use partition 2 to get at the whole disk since
this is the "whole disk" partition in the Sun disk
label.

We really should use slice 0xff which really means
the whole physical disk in the VIO disk protocol.
Otherwise things won't work well on a disk image
that doesn't have a proper disk label on it.

Signed-off-by: David S. Miller <davem@davemloft.net>