qemu_aarch64_virt_defconfig: rely on default Image name for kernel

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

configs/qemu_aarch64_virt_defconfig

@@ -19,5 +19,3 @@ BR2_LINUX_KERNEL_CUSTOM_VERSION=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.2"
 BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
 BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/aarch64-virt/linux-4.2.config"
-BR2_LINUX_KERNEL_IMAGE_TARGET_CUSTOM=y
-BR2_LINUX_KERNEL_IMAGE_TARGET_NAME="Image"