time_interpolator: Use readq_relaxed instead of readq.

On some platforms readq performs additional work to make sure I/O is done in
a coherent way. This is not needed for time retrieval as done by the time interpolator.
So we can use readq_relaxed instead which will improve performance.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.16-rc4/kernel/timer.c
===================================================================
--- linux-2.6.16-rc4.orig/kernel/timer.c	2006-02-17 14:23:45.000000000 -0800
+++ linux-2.6.16-rc4/kernel/timer.c	2006-02-23 14:03:02.000000000 -0800
@@ -1351,10 +1351,10 @@ static inline u64 time_interpolator_get_
 			return x();
 
 		case TIME_SOURCE_MMIO64	:
-			return readq((void __iomem *) time_interpolator->addr);
+			return readq_relaxed((void __iomem *) time_interpolator->addr);
 
 		case TIME_SOURCE_MMIO32	:
-			return readl((void __iomem *) time_interpolator->addr);
+			return readl_relaxed((void __iomem *) time_interpolator->addr);
 
 		default: return get_cycles();
 	}