Delete overscan setting by both unique id and name.

When overscan with only zeros is set, it removes an entry by display's
unique identifier. It turns out in the past the readable name must have
been used in the past and there is a lingering value in the xml file.
This CL purges also the display name entry.

Bug: 22357152
Change-Id: Ie2daf76677eb96df474acb546491194d0aaf8bc0