SystemUI: improve qs tile layout mechanism

Previously we'd have a temp tile array which would hold tiles until we
were ready to do the first layout pass which caused some funky layouts
initially in specific cases. Get rid of the temp tile array and handle
setting tiles in one pass.

Ref: CYNGNOS-1601

Change-Id: Ibfa4994600c55ced80b8292cbefa9aa1f44971ae
Signed-off-by: Roman Birg <roman@cyngn.com>