ice: Implement ethtool ops for channels

Add code to query and set the number of channels on the primary VSI for a
PF. This is accessed from the 'ethtool -l' and 'ethtool -L' commands,
respectively.  Though the ice driver supports asymmetric queues report an
IRQ vector that has both Rx and Tx queues attached and is counted as a
'combined' channel.

Signed-off-by: Henry Tieman <henry.w.tieman@intel.com>
Co-developed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>