setup: handle bookwork config.txt

Bookworm config.txt includes a cm5 specific entry that matched
the search pattern for the dwc2 overlay, so setup wouldn't add
it if needed.

setup/pi/setup-teslausb

@@ -862,7 +862,7 @@ done
 # Update config.txt if needed
 if [ -f "$PICONFIG_PATH" ]
 then
-  if ! grep -q 'dtoverlay=dwc2' "$PICONFIG_PATH"
+  if ! grep -q 'dtoverlay=dwc2$' "$PICONFIG_PATH"
   then
     echo -e "dtoverlay=dwc2\n" >> "$PICONFIG_PATH"
     setup_progress "rebooting to apply dwc2 overlay change"