drm_hwcomposer: Use vector for overlay planes

For two reasons:
1- Because we don't need to use deque
2- Because we'll need to erase from the middle in the future,
   and deque makes that difficult while iterating

BUG=chrome-os-parter:42311
TEST=Tested on smaug, turned on/off bunch of times, no dup icons

Change-Id: I306bdea15d7165f63afeb3b1e06774e2e9a1785f
Signed-off-by: Sean Paul <seanpaul@chromium.org>
2 files changed