[AOA FFS Implementation] Check ro.usb.userspace.aoa.enabled property

This checks the ro.usb.userspace.aoa.enabled property which is set by
device init when enabling the userspace AOA implementation

Bug: 407985367
Bug: 440091110
Flag: android.hardware.usb.flags.enable_aoa_userspace_implementation
Test: Manual - flagging infrastructure
Change-Id: I96ed1133dddabbcf685597179db7fb5bcb154893
Signed-off-by: Neill Kapron <nkapron@google.com>