efi_loader: rename struct efi_initrd_dp to efi_lo_dp_prefix

As we now also store device-tree device-paths in load options rename
struct efi_initrd_dp to efi_lo_dp_prefix.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/lib/efi_loader/efi_load_initrd.c b/lib/efi_loader/efi_load_initrd.c
index d911354..2350843 100644
--- a/lib/efi_loader/efi_load_initrd.c
+++ b/lib/efi_loader/efi_load_initrd.c
@@ -24,7 +24,7 @@
  * Device path defined by Linux to identify the handle providing the
  * EFI_LOAD_FILE2_PROTOCOL used for loading the initial ramdisk.
  */
-static const struct efi_initrd_dp dp_lf2_handle = {
+static const struct efi_lo_dp_prefix dp_lf2_handle = {
 	.vendor = {
 		{
 		   DEVICE_PATH_TYPE_MEDIA_DEVICE,