Revert "Show connected to Wi-Fi hotspot devices"

This reverts commit cd7787b80141244eba7a0edc757731a69b8872b9.
Show connected to Wi-Fi hotspot devices

Change-Id: Icf51db5ae0204ed2bf153a5223aec986d3b496c4
Hide heads up settings and show a notice if heads up is disabled.

This follows a UI pattern used at several other places, such as
daydream, screencast, profiles or blacklist settings.

Change-Id: I5635338ceccae8ba8450284d3078889333fb77c6