patch 8.2.0779: tmode_T not used everywhere

Problem:    Tmode_T not used everywhere.
Solution:   Also use tmode_T for settmode().
diff --git a/src/term.c b/src/term.c
index a575227..11972a1 100644
--- a/src/term.c
+++ b/src/term.c
@@ -3436,7 +3436,7 @@
  * commands and Ex mode).
  */
     void
-settmode(int tmode)
+settmode(tmode_T tmode)
 {
 #ifdef FEAT_GUI
     // don't set the term where gvim was started to any mode