fm10k: Add netconsole support

This change adds a function called "fm10k_netpoll" that's used to define
"ndo_poll_controller" in "fm10k_netdev_ops". This is required to enable
support for "netconsole" in fm10k.

Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Ngai-Mint Kwan <ngai-mint.kwan@intel.com>
Acked-by: Matthew Vick <matthew.vick@intel.com>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>