[SCSI] advansys: Stop using n_io_port in Scsi_Host structure

n_io_port isn't suitable for advansys because some of the boards have
more than 255 bytes of io port space.  There's already a driver-private
replacement, asc_n_io_port, but for some reason the driver was still
setting and occasionally reporting n_io_port.

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