Do not enable Camera widget on non-camera devices

Change-Id: Ib8b945aaf23ecaaf70e6d8ca466d54d97f9982a0
Update 'Wi-Fi display' string to 'Cast screen'

Change-Id: I7205a9bc96d0d560334ecd801511b617d5e1f304
SoundSettings: Assigning a null to an unnecessary variable

Change-Id: Ic8c3e6ff66cc888f6069e3bbef666ede3c56dc13