Updating the touchscreen interface structure (#4596)

Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>
Co-authored-by: NP v/d Spek <github_mail@lumensoft.nl>
Co-authored-by: Clyde Stubbs <2366188+clydebarrow@users.noreply.github.com>
Co-authored-by: Gustavo Ambrozio <gustavo@gustavo.eng.br>

tests/test8.yaml

@@ -54,6 +54,7 @@ spi_device:
 
 display:
   - platform: ili9xxx
+    id: displ8
     model: ili9342
     cs_pin: GPIO5
     dc_pin: GPIO4
@@ -67,6 +68,7 @@ i2c:
 
 touchscreen:
   - platform: tt21100
+    display: displ8
     interrupt_pin:
       number: GPIO3
       ignore_strapping_warning: true