[POWERPC] Bypass hcall stats until cpu features have run

I noticed that we execute hcalls before cpu feature code has run (eg
for setting up the bolted kernel region).  This means that we may be
executing code that is not appropriate for the processor we have.
Create an unconditional branch that we nop out all the time to fix this.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

arch/powerpc/platforms/pseries/hvCall.S

@@ -30,9 +30,14 @@ END_FTR_SECTION_IFSET(CPU_FTR_PURR);
 	
 /*
  * postcall is performed immediately before function return which
- * allows liberal use of volatile registers.
+ * allows liberal use of volatile registers.  We branch around this
+ * in early init (eg when populating the MMU hashtable) by using an
+ * unconditional cpu feature.
  */
 #define HCALL_INST_POSTCALL					\
+BEGIN_FTR_SECTION;						\
+	b	1f;						\
+END_FTR_SECTION(0, 1);						\
 	ld	r4,STK_PARM(r3)(r1);	/* validate opcode */	\
 	cmpldi	cr7,r4,MAX_HCALL_OPCODE;			\
 	bgt-	cr7,1f;						\