x86: compile apm and voyager module only when selected in Kconfig

Previously the complete files were #ifdef'ed, but now handle that in the
Makefile.

May save a minor bit of compilation time.

[ Stephen Rothwell <sfr@canb.auug.org.au>: build dependency fix ]
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index dcad650..349b81a 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -28,9 +28,11 @@
 targets		:= vmlinux.bin setup.bin setup.elf zImage bzImage
 subdir- 	:= compressed
 
-setup-y		+= a20.o apm.o cmdline.o copy.o cpu.o cpucheck.o edd.o
+setup-y		+= a20.o cmdline.o copy.o cpu.o cpucheck.o edd.o
 setup-y		+= header.o main.o mca.o memory.o pm.o pmjump.o
-setup-y		+= printf.o string.o tty.o video.o version.o voyager.o
+setup-y		+= printf.o string.o tty.o video.o version.o
+setup-$(CONFIG_X86_APM_BOOT) += apm.o
+setup-$(CONFIG_X86_VOYAGER) += voyager.o
 
 # The link order of the video-*.o modules can matter.  In particular,
 # video-vga.o *must* be listed first, followed by video-vesa.o.