efi_loader: debug output file handle in efi_file_open()

For debugging it is helpful to know the address of the file handle created
by the Open() method of the EFI file protocol. So let's write it with
EFI_PRINT().

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_loader/efi_file.c b/lib/efi_loader/efi_file.c
index 0483403..be3e55f 100644
--- a/lib/efi_loader/efi_file.c
+++ b/lib/efi_loader/efi_file.c
@@ -257,10 +257,12 @@
 
 	/* Open file */
 	*new_handle = file_open(fh->fs, fh, file_name, open_mode, attributes);
-	if (*new_handle)
+	if (*new_handle) {
+		EFI_PRINT("file handle %p\n", *new_handle);
 		ret = EFI_SUCCESS;
-	else
+	} else {
 		ret = EFI_NOT_FOUND;
+	}
 out:
 	return EFI_EXIT(ret);
 }