powerpc/pmac/smp: Remove HMT changes for PowerMac offline code

Those instructions do nothing on non-threaded processors such
as 970's used on those machines.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/powermac/smp.c

@@ -928,10 +928,6 @@ static void pmac_cpu_die(void)
 		/* should always be true at this point */
 		if (cpu_has_feature(CPU_FTR_CAN_NAP))
 			power4_cpu_offline_powersave();
-		else {
-			HMT_low();
-			HMT_very_low();
-		}
 	}
 }