fix(util/grub-mkrescue): fix EFI executable name for mips64el-efi

Loongson 3A4000/3B4000 firmware expects BOOTMIPS.EFI, not bootmips64el.efi.

Author: MingcongBai

util/grub-mkrescue.c

@@ -830,7 +830,7 @@ main (int argc, char *argv[])
       make_image_abs (GRUB_INSTALL_PLATFORM_RISCV64_EFI, "riscv64-efi", imgname);
       free (imgname);
 
-      imgname = grub_util_path_concat (2, efidir_efi_boot, "bootmips64el.efi");
+      imgname = grub_util_path_concat (2, efidir_efi_boot, "BOOTMIPS.EFI");
       make_image_abs (GRUB_INSTALL_PLATFORM_MIPS64EL_EFI, "mips64el-efi", imgname);
       free (imgname);