aarch64_qemu_boot: Don't repack a new QCOW image

This was a stray config fragment used during development that was
accedentally included in the referenced commit.

Fixes: 0fe5964 ("aarch64_qemu_boot: Restore build after removing post-image.sh")

Author: wkz

configs/aarch64_qemu_boot_defconfig

@@ -24,7 +24,5 @@ BR2_TARGET_UBOOT_FORMAT_DTB=y
 BR2_PACKAGE_HOST_UBOOT_TOOLS=y
 BR2_PACKAGE_HOST_UBOOT_TOOLS_FIT_SUPPORT=y
 BR2_PACKAGE_HOST_UBOOT_TOOLS_FIT_SIGNATURE_SUPPORT=y
-IMAGE_ITB_QCOW=y
-IMAGE_ITB_DL_RELEASE=y
 TRUSTED_KEYS=y
 TRUSTED_KEYS_DEVELOPMENT=y