efi_loader: flesh out device-path to text

It needs to handle more device-path node types, and also multiple levels
of path hierarchy.  To simplify this, initially construct utf8 string to
a temporary buffer, and then allocate the real utf16 buffer that is
returned.  This should be mostly for debugging or at least not critical-
path so an extra copy won't hurt, and is saner than the alternative.

Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/include/efi_loader.h b/include/efi_loader.h
index 29701af..784257b 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -80,6 +80,8 @@
 extern const struct efi_console_control_protocol efi_console_control;
 extern const struct efi_device_path_to_text_protocol efi_device_path_to_text;
 
+uint16_t *efi_dp_str(struct efi_device_path *dp);
+
 extern const efi_guid_t efi_guid_console_control;
 extern const efi_guid_t efi_guid_device_path;
 extern const efi_guid_t efi_guid_loaded_image;