Add float16 support to LSTM op

Fix: 118608162
Test: NeuralNetworksTest_static
Change-Id: I4426183bfd7ce943a7891f0469708848e615ae7a
Merged-In: I4426183bfd7ce943a7891f0469708848e615ae7a
(cherry picked from commit 2fbebe8379a8a0b31b45d6d2241292ee44ed0b41)
46 files changed