of: add 'of_' prefix to machine_is_compatible()

machine is compatible is an OF-specific call.  It should have
the of_ prefix to protect the global namespace.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Michal Simek <monstr@monstr.eu>
diff --git a/drivers/macintosh/windfarm_core.c b/drivers/macintosh/windfarm_core.c
index 075b4d9..437f55c 100644
--- a/drivers/macintosh/windfarm_core.c
+++ b/drivers/macintosh/windfarm_core.c
@@ -468,9 +468,9 @@
 	DBG("wf: core loaded\n");
 
 	/* Don't register on old machines that use therm_pm72 for now */
-	if (machine_is_compatible("PowerMac7,2") ||
-	    machine_is_compatible("PowerMac7,3") ||
-	    machine_is_compatible("RackMac3,1"))
+	if (of_machine_is_compatible("PowerMac7,2") ||
+	    of_machine_is_compatible("PowerMac7,3") ||
+	    of_machine_is_compatible("RackMac3,1"))
 		return -ENODEV;
 	platform_device_register(&wf_platform_device);
 	return 0;