Revert r326083, it doesn't behave as expected.

Even though there do appear to be more artificial frames, with 12, stack
traces no longer list at all.  Revert until a better, more stable value can
be determined.

sys/cddl/dev/profile/profile.c

@@ -124,7 +124,7 @@
 /*
  * This value is bogus just to make module compilable on powerpc
  */
-#define	PROF_ARTIFICIAL_FRAMES	12
+#define	PROF_ARTIFICIAL_FRAMES	3
 #endif
 
 struct profile_probe_percpu;