[master] Trivial typo on 4o6-subnet flex action

src/bin/dhcp4/dhcp4_lexer.ll

@@ -1194,7 +1194,7 @@ ControlCharacterFill            [^"\\]|\\{JSONEscapeSequence}
     case isc::dhcp::Parser4Context::SUBNET4:
         return isc::dhcp::Dhcp4Parser::make_SUBNET_4O6_SUBNET(driver.loc_);
     default:
-        return isc::dhcp::Dhcp4Parser::make_STRING("4o6-interface", driver.loc_);
+        return isc::dhcp::Dhcp4Parser::make_STRING("4o6-subnet", driver.loc_);
     }
 }