remove unnecessary int8_t casts that cause warnings
remove unnecessary int8_t casts that cause warnings

dariaphoebe/mux2005-dhcptool,dariaphoebe/mux2005-dhcptool,dbrashear/mux2005-dhcptool,mbenkmann/dhcptool,mbenkmann/dhcptool,dbrashear/mux2005-dhcptool