arm: fix compilation with CONFIG_FDT

A conflict was resolved the wrong way when merging commit 320ba5fe (build:
always link device_tree.o into emulators if libfdt available, 2013-02-05).
This causes a build failure for the arm-softmmu target due to multiply
defined symbol.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-id: 1362997886-9470-1-git-send-email-pbonzini@redhat.com
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

hw/arm/Makefile.objs

@@ -23,7 +23,6 @@ obj-y += bitbang_i2c.o marvell_88w8618_audio.o
 obj-y += framebuffer.o
 obj-y += strongarm.o
 obj-y += imx_serial.o imx_ccm.o imx_timer.o imx_avic.o
-obj-$(CONFIG_FDT) += ../device_tree.o
 obj-$(CONFIG_KVM) += kvm/arm_gic.o
 
 obj-y := $(addprefix ../,$(obj-y))