[SCSI] sym53c8xx: Remove pci_dev pointer from sym_shcb

This structure is accessed by the device; the fewer Linux things in it,
the better.  Using the pci_dev pointer from the hostdata requires a lot
of changes:

 - Pass Scsi_Host to a lot of routines which currently take a sym_hcb.
 - Set the Scsi_Host as the pci drvdata (instead of the sym_hcb)

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>