update vyos driver to use set_base_prompt from parent
update vyos driver to use set_base_prompt from parent

isidroamv/netmiko,shamanu4/netmiko,shamanu4/netmiko,shsingh/netmiko,fooelisa/netmiko,ktbyers/netmiko,isidroamv/netmiko,shsingh/netmiko,fooelisa/netmiko,ktbyers/netmiko