[SCSI] advansys: Convert to ISA driver model

Register two isa_drivers, one for ISA and one for VLB, in order to
preserve detection order.  When deleting advansys_detect, we lose the
last vestiges of the code that limited IO port scanning.  This code
has been effectively disabled for many years anyway; I'll restore it
in a module_param later.  We also lose the code that placed all ISA PnP
cards into WaitForKey state -- drivers shouldn't be doing this anyway.
The asc_host array goes away too.  Also remove some IOADR and other
definitions, such as ASC_NUM_BOARD_SUPPORTED.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>