On Yeeloong, pass machine type information to Linux.
* grub-core/loader/mips/linux.c [GRUB_MACHINE_MIPS_YEELOONG]
(LOONGSON_MACHTYPE): New macro, set to
"machtype=lemote-yeeloong-2f-8.9inches".
[LOONGSON_MACHTYPE] (grub_cmd_linux): Pass LOONGSON_MACHTYPE as
additional argument to Linux.