[calls] ui-call-data: Remove unused struct

[Evangelos Ribeiro Tzaras <devrtz src gnome org>]

commit f01c99c587d493db28208eecbb0e8e5c9dd52609
Author: Evangelos Ribeiro Tzaras <devrtz fortysixandtwo eu>
Date:   Thu Jan 13 15:39:07 2022 +0100

    ui-call-data: Remove unused struct

 src/calls-ui-call-data.c | 6 ------
 1 file changed, 6 deletions(-)
---
diff --git a/src/calls-ui-call-data.c b/src/calls-ui-call-data.c
index 19ddb396..dc8407f8 100644
--- a/src/calls-ui-call-data.c
+++ b/src/calls-ui-call-data.c
@@ -56,12 +56,6 @@ G_DEFINE_TYPE_WITH_CODE (CallsUiCallData, calls_ui_call_data, G_TYPE_OBJECT,
                          G_IMPLEMENT_INTERFACE (CUI_TYPE_CALL,
                                                 calls_ui_call_data_cui_call_interface_init))
 
-struct DtmfData
-{
-  CallsCall *call;
-  char dtmf;
-};
-
 static const char *
 calls_ui_call_data_get_display_name (CuiCall *call_data)
 {