[SCSI] advansys: Convert to PCI driver model

 - Add a pci_driver interface for the PCI advansys devices (for
   ISA/EISA/VLB devices, we still call advansys_detect).
 - Many functions are converted from __init to __devinit to allow hotplug
   PCI to work.
 - Only keep devices found by advansys_detect in the asc_host list.
 - Rename asc_board_count to asc_legacy_count.  New asc_board_count is only
   used to generate a unique name for each device.
 - Remove some now-unused macros and struct definitions

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