Use rounding in requantize.

This is to avoid a systematic bias of ops using requantize.

Fixes: 134078526
Test: NeuralNetworksTest_static
Change-Id: I3f64f5b2d5778bfe613707cfa252f67e87dce9c5
Merged-In: I3f64f5b2d5778bfe613707cfa252f67e87dce9c5
(cherry picked from commit 654b735b8196ed5b703d73f3e4ab8a9bc354d471)