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_cpufreq_clamp.c b/drivers/macintosh/windfarm_cpufreq_clamp.c
index 900aade..1a77a7c 100644
--- a/drivers/macintosh/windfarm_cpufreq_clamp.c
+++ b/drivers/macintosh/windfarm_cpufreq_clamp.c
@@ -76,9 +76,9 @@
 	struct wf_control *clamp;
 
 	/* 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;
 
 	clamp = kmalloc(sizeof(struct wf_control), GFP_KERNEL);