Change HIDL fmq tests to use int32_t for payload am: 0a10d6918c am: 606d2ec362 am: 5b1514cb70

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/1431692

Change-Id: I42c80aa8cd2e182167ac3e930f573b31045d6118