Improve SOFTMAX tests The old tests wouldn't cover one of the quantized execution paths. Fix: 129572081 Test: NeuralNetworksTest_static Change-Id: I0a4036536d7019d49bbe335b2ec971d990fa3d2a Merged-In: I0a4036536d7019d49bbe335b2ec971d990fa3d2a (cherry picked from commit 0a5addd76344fddfb680f575f6309009517d68d7)