Fix a type conversion bug.

Convert int64_t to long on x86 platform loses info.

Test: atest FakeVehicleHardwareTest on cf_gwear_x86.
Bug: 288376096
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:76aaef448fcd9458b07b1d78ea4b79165af0cde0)
Merged-In: I8826e2c0ba6c3e26af858a1d8f1388b75d537082
Change-Id: I8826e2c0ba6c3e26af858a1d8f1388b75d537082