ipc_us: clear request unused fields
ipc_us: clear request unused fields

Clear unused request fields and padding so that valgrind doesn't complain
about undefined data being sent over the socket.

kgaillot/libqb,davidvossel/libqb,kgaillot/libqb,kgaillot/libqb,ClusterLabs/libqb,gao-yan/libqb,ClusterLabs/libqb,davidvossel/libqb,gao-yan/libqb,rubenk/libqb,rubenk/libqb,ClusterLabs/libqb