configs/qemu: convert versatile to dt

As a followup to http://patchwork.ozlabs.org/patch/548550/ fully convert
the versatile defconfig to create the dtb and update the instructions.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

board/qemu/arm-versatile/linux-4.4.config

@@ -3,6 +3,7 @@ CONFIG_MODULES=y
 CONFIG_MODULE_UNLOAD=y
 CONFIG_ARCH_VERSATILE=y
 CONFIG_MACH_VERSATILE_AB=y
+CONFIG_MACH_VERSATILE_DT=y
 CONFIG_PCI=y
 CONFIG_AEABI=y
 CONFIG_USE_OF=y

board/qemu/arm-versatile/readme.txt

@@ -1,6 +1,6 @@
 Run the emulation with:
 
-  qemu-system-arm -M versatilepb -kernel output/images/zImage -drive file=output/images/rootfs.ext2,if=scsi,format=raw -append "root=/dev/sda console=ttyAMA0,115200" -serial stdio -net nic,model=rtl8139 -net user
+  qemu-system-arm -M versatilepb -kernel output/images/zImage -dtb output/images/versatile-pb.dtb -drive file=output/images/rootfs.ext2,if=scsi,format=raw -append "root=/dev/sda console=ttyAMA0,115200" -serial stdio -net nic,model=rtl8139 -net user
 
 The login prompt will appear in the terminal that started Qemu. The
 graphical window is the framebuffer.

configs/qemu_arm_versatile_defconfig

@@ -20,3 +20,5 @@ BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.4.1"
 BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
 BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/arm-versatile/linux-4.4.config"
 BR2_LINUX_KERNEL_ZIMAGE=y
+BR2_LINUX_KERNEL_DTS_SUPPORT=y
+BR2_LINUX_KERNEL_INTREE_DTS_NAME="versatile-pb"