efi_loader: consistent naming of protocol GUIDs

We should consistently use the same name for protocol GUIDs as defined in
the UEFI specification. Not adhering to this rule has led to duplicate
definitions for the EFI_LOADED_IMAGE_PROTOCOL_GUID.

Adjust misnamed protocol GUIDs.

Adjust the text for the graphics output protocol in the output of the
`efidebug dh` command.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_selftest/efi_selftest_devicepath.c b/lib/efi_selftest/efi_selftest_devicepath.c
index 105ce2c..4ce3fad 100644
--- a/lib/efi_selftest/efi_selftest_devicepath.c
+++ b/lib/efi_selftest/efi_selftest_devicepath.c
@@ -20,7 +20,7 @@
 	void (EFIAPI * inc)(void);
 } interface;
 
-static efi_guid_t guid_device_path = DEVICE_PATH_GUID;
+static efi_guid_t guid_device_path = EFI_DEVICE_PATH_PROTOCOL_GUID;
 
 static efi_guid_t guid_device_path_to_text_protocol =
 	EFI_DEVICE_PATH_TO_TEXT_PROTOCOL_GUID;