x86: qemu: do not build car.o with start64.o

car.o can only be used with start.o, not with start64.o.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/cpu/qemu/Makefile

@@ -2,6 +2,9 @@
 #
 # Copyright (C) 2015, Bin Meng <bmeng.cn@gmail.com>
 
-obj-y += car.o dram.o
+ifndef CONFIG_$(SPL_)X86_64
+obj-y += car.o
+endif
+obj-y += dram.o
 obj-y += qemu.o
 obj-$(CONFIG_QFW) += cpu.o e820.o