net/i40e: stop LLDP before setting local LLDP MIB

net/i40e: stop LLDP before setting local LLDP MIB

>From the Intel Ethernet Controller X710/XXV710/XL710 Specification
Update:

    Starting from NVM 5.02, if the Set Local LLDP MIB command is
    received while the DCBx specific agent is stopped, the command
    returns an EPERM error. If the command is received while the
    LLDP agent is stopped, it sets the local MIB without exchanging
    LLDP with peer, and returns SUCCESS.

This results in the harmless, but annoying, diagnostic:

    default dcb config fails. err = -53, aq_err = 1.

So, if possible (older firmwares cannot safely stop LLDP), stop the
LLDP daemon when we are in software mod before we attempt to call
i40e_set_dcb_config.

Signed-off-by: Chas Williams <chas3@att.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>