Fix VP9_mode_order[]

Mis-merge of the following change managed to break mode order
and delete two mode options (new alt ref and near alt ref)
It also created a situation where we could test two undefined
modes off the end of the VP9_mode_order[] data structure.
  "clang warnings : remove split and i4x4_pred fake modes"
  "Change Id: I8ef3c*"

Initial testing on Akiyo at speed 2.
101.35	 44.567	 44.447 improves to
96.82	 44.915	 44.815

Approx 0.3-0.4db gain and 2.5% size reduction

Change-Id: Icff813e7c0778d140ad4f0eea18cf1ed203c4e34