[QS] Load text from the ethernet description

EthernetInteractor just emits Icon objects, and we use the content
description to drive the QS internet tile label.

This change fixes an issue where we were just calling toString() on the
ContentDescription object rather than loading its text.

Test: InternetTileViewModelTest
Fixes: 313828907
Flag: NONE
Change-Id: I2db13fc12aecde5d5586a84f89f5a38aafe9d442