linuxloader/initramfs: Add support for loongarch64

Add support for loongarch64 to:

linuxloader
core-image-minimal-initramfs
initramfs-module-install

Signed-off-by: Jialing Zhang <zhangjialing@loongson.cn>
Signed-off-by: Qizheng Zhu <zhuqizheng@loongson.cn>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>