IB/ipath: Add flag and handling for chips with swapped register bug

The 6110 had a bug that caused some registers to be swapped; it was
fixed for the 7220 (and didn't affect the 6120 because it had fewer
registers).  This adds a flag and related code to handle that, and
includes some minor cleanups in the same area.

Signed-off-by:  Ralph Campbell <ralph.campbell@qlogic.com>

drivers/infiniband/hw/ipath/ipath_intr.c

@@ -831,8 +831,8 @@ void ipath_clear_freeze(struct ipath_devdata *dd)
 	 */
 	for (i = 0; i < dd->ipath_pioavregs; i++) {
 		/* deal with 6110 chip bug */
-		im = i > 3 ? ((i&1) ? i-1 : i+1) : i;
-		val = ipath_read_kreg64(dd, (0x1000/sizeof(u64))+im);
+		im = i > 3 ? i ^ 1 : i;
+		val = ipath_read_kreg64(dd, (0x1000 / sizeof(u64)) + im);
 		dd->ipath_pioavailregs_dma[i] = dd->ipath_pioavailshadow[i]
 			= le64_to_cpu(val);
 	}