MIPS: Unbreak function tracer for 64-bit kernel.

Commit 58b69401c797 [MIPS: Function tracer: Fix broken function tracing]
completely broke the function tracer for 64-bit kernels.  The symptom is
a system hang very early in the boot process.

The fix: Remove/fix $sp adjustments for 64-bit case.

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Cc: Al Cooper <alcooperx@gmail.com>
Cc: viric@viric.name
Cc: stable@vger.kernel.org # 3.8.x
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/mcount.S

@@ -46,10 +46,9 @@
 	PTR_L	a5, PT_R9(sp)
 	PTR_L	a6, PT_R10(sp)
 	PTR_L	a7, PT_R11(sp)
-#else
-	PTR_ADDIU	sp, PT_SIZE
 #endif
-.endm
+	PTR_ADDIU	sp, PT_SIZE
+	.endm
 
 	.macro RETURN_BACK
 	jr ra
@@ -68,7 +67,11 @@ NESTED(ftrace_caller, PT_SIZE, ra)
 	.globl _mcount
 _mcount:
 	b	ftrace_stub
-	addiu sp,sp,8
+#ifdef CONFIG_32BIT
+	 addiu sp,sp,8
+#else
+	 nop
+#endif
 
 	/* When tracing is activated, it calls ftrace_caller+8 (aka here) */
 	lw	t1, function_trace_stop