Fix memory leak

Bug: 192998820
Test: atest VtsHalNeuralnetworksV1_2BenchmarkTestCases (with additional
logging on model construction and destruction)
Test: atest VtsHalNeuralnetworksV1_3BenchmarkTestCases

Change-Id: Ic9f51474fac5a87265660340a8bf91b250c33887
Merged-In: Ic9f51474fac5a87265660340a8bf91b250c33887
(cherry picked from commit 3f7b316013d99808ef76c835cdca12758a82ae6e)
2 files changed