TBR syncbase: Add a channel timeout to the GetDeltas RPC.
TBR syncbase: Add a channel timeout to the GetDeltas RPC.

This will ensure that if the remote end goes silent, the RPC will
fail.

Change-Id: I408a9a60d7b0c3449cb9e84834328e51f2cac70d

vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref