CFBMC-4521: AFF A800 BMC API reachability errors after fw upgrade from 10.8 to 10.9

Issue

After a BMC firmware update to version 10.9, the [::> system node autosupport manifest show -node * -body-file platform-sensors.xml] outputs are similar to:
     [The Service Processor on node "node_name" is not reachable. Verify that the SP or BMC is online, verify that api-service is enabled on the SP or BMC, verify that the partner node is running, check if pings from SP or BMC to partner node work, check if hw-assist keep-alives are normal, check that network ports are configured correctly and are functional (up). Then, try the command again.]
 
Checking [::> system service-processor api-service check -node node_name] there is an error at [Local Private IPv4: failed]. Example:
     [Node: node_name]
     [Port: 50000]
     [   Local Private IPv4: failed (192.0.2.81) (ping failed)]
     [Local Public IPv4: ok (<BMC_IP>)
     [...]
 
BMC outputs for [> bmc status -d] are similar to:
     [ [kern_servprocd:info:7973] bmc_set_privlanconfig_to_chip:return err(-1)
     [ [kern_servprocd:info:7973] bmc_set_privlanconfig_to_chip: netmask set failed ]
     [ [kern_servprocd:info:7973] 0x808cd4e00: 0: ERR: Servprocd::SPConfig: manage_ipmi_tasks : Failed to set BMC priv lan. ]
     [ [kern_servprocd:info:7973] 0x808cd4e00: 0: ERR: Servprocd::SPConfig: manage_ipmi_tasks : GET priv LANCONFIG : Network config from BMC 0.0.0.0 0.0.0.0 ]