Move requantize function to OperationsUtils.h

The function is useful for SELECT op implementation and possibly for
some other ops supporting inputs with different quantization parameters.

Test: NeuralNetworksTest_static
Change-Id: I1d835451b9728acf813009861abd5a04a07bb73f
Merged-In: I1d835451b9728acf813009861abd5a04a07bb73f
(cherry picked from commit 7c158207c5120dd75854465c6c975d39b40a1ec1)
3 files changed