from commit c98ee4dbb3db0f064d990941cdd82e872da76946
agent-type takes 1 of 3 possible keywords which do not require quoting:
configure lldp agent-type nearest-bridge | nearest-non-tpmr-bridge
| nearest-customer-bridge
Tested on 22.03.5
Signed-off-by: Paul Donald <newtwen@gmail.com>