w32_common: stop IME initialization timer after first try

It will be set again on first key press, but no need to call IME api
every 250ms until any key is pressed.

video/out/w32_common.c

@@ -1752,6 +1752,7 @@ static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam,
         if (wParam == WM_CREATE) {
             // Default to alphanumeric input when the IME is first initialized.
             set_ime_conversion_mode(w32, IME_CMODE_ALPHANUMERIC);
+            KillTimer(w32->window, (UINT_PTR)WM_CREATE);
             return 0;
         }
         break;