zorro: ZTWO_VADDR() should return "void __iomem *"

ZTWO_VADDR() converts from physical to virtual I/O addresses, so it should
return "void __iomem *" instead of "unsigned long".

This allows to drop several casts, but requires adding a few casts to
accomodate legacy driver frameworks that store "unsigned long" I/O
addresses.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
diff --git a/drivers/scsi/a2091.c b/drivers/scsi/a2091.c
index 30fa38a..9176bfb 100644
--- a/drivers/scsi/a2091.c
+++ b/drivers/scsi/a2091.c
@@ -201,7 +201,7 @@
 	instance->irq = IRQ_AMIGA_PORTS;
 	instance->unique_id = z->slotaddr;
 
-	regs = (struct a2091_scsiregs *)ZTWO_VADDR(z->resource.start);
+	regs = ZTWO_VADDR(z->resource.start);
 	regs->DAWR = DAWR_A2091;
 
 	wdregs.SASR = &regs->SASR;