external/webkit: use Cpu Upload path

Use Cpu Upload mode since the Gpu mode is not working
and expected to be slower.

Change-Id: Iacb6de4a4e054e4f6ebb07d8a8209228e78e5ee0
Merge remote-tracking branch 'rebel/kk_2.7_rb1.16' into kk_2.7_rb1.16