ARM emulator: aosp_arm on 64-bit binder and kernel

Starting in P, all 32-bit and 64-bit architectures use 64-bit
binder interface. This is similar to ag/3576770 for x86.

Bug: 71861550
Test: the following products can boot to home screen successfully:
    lunch aosp_arm-userdebug; m -j; emulator
    lunch sdk_phone_armv7-userdebug; m -j; emulator
Change-Id: Ibe1f53a5798342555e2e84395a13b48d461f483d