armvirt: merge arm64 as subtarget 64

Original armvirt target is now subtarget 32.  Other than that the built
result should remain the same as before

Besides old features already available with arm64, the new armvirt/64
subtarget will also have those features originally enabled for
armvirt/32 with commit 44ecfc2 ("armvirt: new target")
 - pl011, uart
 - pl031, rtc
 - pl061, gpio
 - pci-host-generic
 - virtio_{mmio,pci,net,blk,scsi,9p,console,balloon}
 - smp with NR_CPUS=4
 - cpu-hotplug
 - ext4
 - DEBUG_BUGVERBOSE for debug purposes

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

target/linux/armvirt/Makefile

@@ -1,28 +1,20 @@
 #
-# Copyright (C) 2016 Yousong Zhou <yszhou4tech@gmail.com>
+# Copyright (C) 2017 Yousong Zhou <yszhou4tech@gmail.com>
 #
 # This is free software, licensed under the GNU General Public License v2.
 # See /LICENSE for more information.
 #
 include $(TOPDIR)/rules.mk
 
-ARCH:=arm
 BOARD:=armvirt
 BOARDNAME:=QEMU ARM Virtual Machine
 FEATURES:=fpu pci rtc usb
 FEATURES+=cpiogz ext4 ramdisk squashfs targz
-CPU_TYPE:=cortex-a15
-CPU_SUBTYPE:=neon-vfpv4
-MAINTAINER:=Yousong Zhou <yszhou4tech@gmail.com>
+MAINTAINER:=Florian Fainelli <f.fainelli@gmail.com>, \
+	Yousong Zhou <yszhou4tech@gmail.com>
 
-KERNEL_PATCHVER:=4.4
-
-define Target/Description
-  Build images for QEMU ARM Virtual Machine
-endef
+KERNEL_PATCHVER:=4.9
 
 include $(INCLUDE_DIR)/target.mk
 
-KERNELNAME:=zImage
-
 $(eval $(call BuildTarget))