i40e: Log disable-fw-lldp flag change by ethtool

Add logging for disable-fw-lldp flag by ethtool. Added check
for I40E_FLAG_DISABLE_FW_LLDP and logging state in dmesg.
Without this commit there was no clear statement in dmesg
about FW LLDP state in dmesg.

Signed-off-by: Slawomir Laba <slawomirx.laba@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>