Fix mpii(4) on 32bit.

The expression results in a signed extension from 32bit to 64bit,
resulting in the higher word being 0xffffffff on 32bit systems:

The expression is bus_addr_t + caddr_t - caddr_t, which is:
(bus_addr_t + caddr_t) - caddr_t,
which is (u_long + (char *)) - (char *),
u_long + char * == signed 32bit pointer, which then
gets subtracted, which then gets signed extended to 64bit.

ok pedro@

Author: haesbaert

sys/dev/pci/mpii.c

@@ -773,7 +773,7 @@ mpii_load_xs(struct mpii_ccb *ccb)
 			    MPII_SGE_FL_SIZE_64 | len);
 			/* address of the next sge */
 			mpii_dvatosge(csge, ccb->ccb_cmd_dva +
-			    (caddr_t)nsge - (caddr_t)io);
+			    ((bus_addr_t)nsge - (bus_addr_t)io));
 		}
 
 		sge = nsge;