floss: avrcp: uinput: fix unsafe code type mismatch for arm

Fix type mismatch when not using libc:: types but u64, char, etc.
Update all types that are used by unsafe code to be libc:: compatible.

Bug: 244317214
Tag: #floss
Test: emerge-brya floss
Test: emerge-arm-generic floss
Test: ./build.py
Change-Id: I7843fa13451d9000f5a173214af27ef5eb62a50c