Use only a single TileLayout in QSPanel

The layout is the same regardless of the media configuration for both
QSPanel and QuickQSPanel, the only thing that changes is the number of
columns/rows.

Remove code maintaining two possible TileLayouts, including code that
destroyed and recreated the views.

Test: manual, change orientation with and without media
Fixes: 191948961
Change-Id: I80356b5dde787722cbae3a5eb757a5d458529a29