Manually set mLastTileBottom when not laying out

We want to use the correct bottom when using squishiness. As we cannot
override `setLeftTopRightBottom` in QSTileViewImpl, we manually set it
using the correct scale.

Test: manual
Fixes: 225405454
Change-Id: I9e6905a68fcb076842bb189bc75396067b6dfaa2
2 files changed