[openwrt/openwrt] ath79: mikrotik: use OpenWrt loader for initram image

[LEDE Commits]

hauke pushed a commit to openwrt/openwrt.git, branch openwrt-22.03:
https://git.openwrt.org/68add5f3645493cac3632d994f76928648a6cc59

commit 68add5f3645493cac3632d994f76928648a6cc59
Author: John Thomson <git at johnthomson.fastmail.com.au>
AuthorDate: Sat Nov 19 11:01:17 2022 +0100

    ath79: mikrotik: use OpenWrt loader for initram image
    
    Return to using the OpenWrt kernel loader to decompress and load kernel
    initram image.
    
    Continue to use the vmlinuz kernel for squashfs.
    
    Mikrotik's bootloader RouterBOOT on some ath79 devices is
    failing to boot the current initram, due to the size of the initram image.
    
    On the ath79 wAP-ac:
    a 5.7MiB initram image would fail to boot
    After this change:
    a 6.6MiB initram image successfully loads
    
    This partially reverts commit e91344776b9ba7c864be88d915c9c0df0eb790dd.
    
    An alternative of using RouterBOOT's capability of loading an initrd ELF
    section was investigated, but the OpenWrt kernel loader allows larger image.
    
    Signed-off-by: John Thomson <git at johnthomson.fastmail.com.au>
    (cherry picked from commit 62b72eafe49d2eecd3692691152ed86a0327fcb0)
    Signed-off-by: Thibaut VARÈNE <hacks at slashdirt.org>
    Fixes: #9954
---
 target/linux/ath79/image/common-mikrotik.mk | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/target/linux/ath79/image/common-mikrotik.mk b/target/linux/ath79/image/common-mikrotik.mk
index 5f5fa7899a..fb3dc78226 100644
--- a/target/linux/ath79/image/common-mikrotik.mk
+++ b/target/linux/ath79/image/common-mikrotik.mk
@@ -1,8 +1,10 @@
 define Device/mikrotik
 	DEVICE_VENDOR := MikroTik
+	LOADER_TYPE := elf
 	KERNEL_NAME := vmlinuz
 	KERNEL := kernel-bin | append-dtb-elf
-	KERNEL_INITRAMFS := kernel-bin | append-dtb-elf
+	KERNEL_INITRAMFS_NAME := vmlinux-initramfs
+	KERNEL_INITRAMFS := kernel-bin | append-dtb | lzma | loader-kernel
 endef
 
 define Device/mikrotik_nor