powerpc: Fix typo in head_64.S

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 881e18e..65aedc9 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -727,7 +727,7 @@
 	li	r11,1
 	stb	r11,PACALPPACA+LPPACADECRINT(r13)
 	LOADBASE(r12,tb_ticks_per_jiffy)
-	lwz	r12,OFF(tb_ticks_per_jiffy)(r13)
+	lwz	r12,OFF(tb_ticks_per_jiffy)(r12)
 	mtspr	SPRN_DEC,r12
 	/* fall through */