ARM: mvebu: compile pm code conditionally

A cleanup to include the headers correctly caused another build problem:

arch/arm/mach-mvebu/kirkwood-pm.c:70:13: error: redefinition of 'kirkwood_pm_init'
arch/arm/mach-mvebu/kirkwood-pm.h:23:20: note: previous definition of 'kirkwood_pm_init' was here

The underlying issue is that kirkwood-pm.o is not actually meant to be
used when CONFIG_PM is disabled, so we should also leave it out of the
Makefile.

The same seems to be true for the PM code in MACH_MVEBU_V7, and I'm
treating it the same way here.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: d705c1a66e ("ARM: Kirkwood: fix kirkwood_pm_init() declaration/type")
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>

arch/arm/mach-mvebu/Makefile

@@ -7,9 +7,15 @@ CFLAGS_pmsu.o			:= -march=armv7-a
 obj-$(CONFIG_MACH_MVEBU_ANY)	 += system-controller.o mvebu-soc-id.o
 
 ifeq ($(CONFIG_MACH_MVEBU_V7),y)
-obj-y				 += cpu-reset.o board-v7.o coherency.o coherency_ll.o pmsu.o pmsu_ll.o pm.o pm-board.o
+obj-y				 += cpu-reset.o board-v7.o coherency.o coherency_ll.o pmsu.o pmsu_ll.o
+
+obj-$(CONFIG_PM)		 += pm.o pm-board.o
 obj-$(CONFIG_SMP)		 += platsmp.o headsmp.o platsmp-a9.o headsmp-a9.o
 endif
 
 obj-$(CONFIG_MACH_DOVE)		 += dove.o
-obj-$(CONFIG_MACH_KIRKWOOD)	 += kirkwood.o kirkwood-pm.o
+
+ifeq ($(CONFIG_MACH_KIRKWOOD),y)
+obj-y				 += kirkwood.o
+obj-$(CONFIG_PM)		 += kirkwood-pm.o
+endif