sys-kernel/coreos-modules: Enable EFI_ZBOOT for arm64

Arm64 now supports booting a compressed kernel through EFI. This is
hidden behind the EFI_ZBOOT Kconfig option. The EFI_ZBOOT is only
enabled in the arm64 config because it is not available for x86. X86
relies on an architecture specific compression mechanism on EFI. The
KERNEL_ZSTD Kconfig option applies to both arches so move it to
commonconfig. The other change required is that the kernel image name
changes.

In my local build it looks like the kernel size goes down from 59MB to
43MB.

Signed-off-by: Jeremi Piotrowski <jpiotrowski@microsoft.com>

Author: jepio

sdk_container/src/third_party/coreos-overlay/eclass/coreos-kernel.eclass

@@ -100,7 +100,7 @@ config_update() {
 kernel_path() {
 	local kernel_arch=$(tc-arch-kernel)
 	case "${kernel_arch}" in
-		arm64)	echo build/arch/arm64/boot/Image;;
+		arm64)	echo build/arch/arm64/boot/vmlinuz.efi;;
 		x86)	echo build/arch/x86/boot/bzImage;;
 		*)		die "Unsupported kernel arch '${kernel_arch}'";;
 	esac

sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-modules/files/amd64_defconfig-6.6

@@ -71,7 +71,6 @@ CONFIG_ISCSI_IBFT_FIND=y
 CONFIG_ITCO_VENDOR_SUPPORT=y
 CONFIG_ITCO_WDT=m
 CONFIG_IGC=m
-CONFIG_KERNEL_ZSTD=y
 CONFIG_KEXEC_FILE=y
 CONFIG_KPROBES_ON_FTRACE=y
 CONFIG_KVM=m

sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-modules/files/arm64_defconfig-6.6

@@ -32,6 +32,7 @@ CONFIG_CRYPTO_SHA1_ARM64_CE=y
 CONFIG_CRYPTO_SHA2_ARM64_CE=y
 # CONFIG_DEBUG_PREEMPT is not set
 CONFIG_DM_DEBUG=y
+CONFIG_EFI_ZBOOT=y
 CONFIG_FB_ARMCLCD=y
 CONFIG_GPIO_PL061=y
 CONFIG_GPIO_XGENE=y

sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-modules/files/commonconfig-6.6

@@ -408,6 +408,7 @@ CONFIG_JME=m
 CONFIG_JOLIET=y
 CONFIG_JUMP_LABEL=y
 CONFIG_KALLSYMS_ALL=y
+CONFIG_KERNEL_ZSTD=y
 CONFIG_KEXEC=y
 CONFIG_KEYS=y
 CONFIG_KEY_DH_OPERATIONS=y