[POWERPC] Move lowlevel runlatch calls under cpu feature control

There's no need to call the runlatch on functions on processors that
don't implement them (CPU_FTR_CTRL).
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/head_64.S

@@ -656,7 +656,9 @@ hardware_interrupt_common:
 	FINISH_NAP
 hardware_interrupt_entry:
 	DISABLE_INTS
+BEGIN_FTR_SECTION
 	bl	.ppc64_runlatch_on
+END_FTR_SECTION_IFSET(CPU_FTR_CTRL)
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	.do_IRQ
 	b	.ret_from_except_lite

include/asm-powerpc/exception.h

@@ -282,7 +282,9 @@ label##_common:						\
 	EXCEPTION_PROLOG_COMMON(trap, PACA_EXGEN);	\
 	FINISH_NAP;					\
 	DISABLE_INTS;					\
+BEGIN_FTR_SECTION					\
 	bl	.ppc64_runlatch_on;			\
+END_FTR_SECTION_IFSET(CPU_FTR_CTRL)			\
 	addi	r3,r1,STACK_FRAME_OVERHEAD;		\
 	bl	hdlr;					\
 	b	.ret_from_except_lite