dtrace/powerpc: Adjust AFRAMES for fbt and profile

FBT_AFRAMES was skipping over too many frames, while PROFILE_AFRAMES was
skipping over too few.  Adjust them empirically.

(cherry picked from commit 635ecbf470)

sys/cddl/dev/fbt/powerpc/fbt_isa.c

@@ -48,7 +48,7 @@
 
 #define	FBT_ENTRY	"entry"
 #define	FBT_RETURN	"return"
-#define	FBT_AFRAMES	7
+#define	FBT_AFRAMES	5
 
 int
 fbt_invop(uintptr_t addr, struct trapframe *frame, uintptr_t rval)

sys/cddl/dev/profile/profile.c

@@ -108,7 +108,7 @@
 /*
  * This value is bogus just to make module compilable on powerpc
  */
-#define	PROF_ARTIFICIAL_FRAMES	3
+#define	PROF_ARTIFICIAL_FRAMES	8
 #endif
 
 struct profile_probe_percpu;