powerpc/windfarm: Updates to lm75 and max6690 sensors

This allows those modules to load on PowerMac7,2 PowerMac7,3
and RackMac3,1 and add the sensor name conversion for those
machines.

This will be used by the corresponding new windfarm modules
for those machines.

Note that since therm_pm72 is linked first, it will still
take priority on those i2c devices if built-in. If using modules
it will depend which is loaded first, but you should avoid building
therm_pm72 if you are using the new windfarm drivers

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/drivers/macintosh/windfarm_max6690_sensor.c b/drivers/macintosh/windfarm_max6690_sensor.c
index f4902f4..371b058 100644
--- a/drivers/macintosh/windfarm_max6690_sensor.c
+++ b/drivers/macintosh/windfarm_max6690_sensor.c
@@ -74,7 +74,11 @@
 		return -ENXIO;
 	}
 
-	if (!strcmp(loc, "BACKSIDE"))
+	/*
+	 * We only expose the external temperature register for
+	 * now as this is all we need for our control loops
+	 */
+	if (!strcmp(loc, "BACKSIDE") || !strcmp(loc, "SYS CTRLR AMBIENT"))
 		name = "backside-temp";
 	else if (!strcmp(loc, "NB Ambient"))
 		name = "north-bridge-temp";
@@ -128,11 +132,6 @@
 
 static int __init wf_max6690_sensor_init(void)
 {
-	/* Don't register on old machines that use therm_pm72 for now */
-	if (of_machine_is_compatible("PowerMac7,2") ||
-	    of_machine_is_compatible("PowerMac7,3") ||
-	    of_machine_is_compatible("RackMac3,1"))
-		return -ENODEV;
 	return i2c_add_driver(&wf_max6690_driver);
 }