radio: fix compatibility for 64 bit processes

Clarify use of 32 bit quantities in all internal and HAL structures
to make sure that structures can be passed through binder calls between
processes with different data unit sizes.

NOTE: some structures still contain a pointer to metadata buffer: This pointer
is always at the end of the structures and special care is taken in binder
call implementations to cope with pointer size differences.

Change-Id: I2023f70c3c62f6fa45f9eab3f09d18033f0efe4f