igc: Refactor XDP rxq info registration

Refactor XDP rxq info registration code, preparing the driver for AF_XDP
zero-copy support which is added by upcoming patches.

Currently, xdp_rxq and memory model are both registered during RX
resource setup time by igc_xdp_register_rxq_info() helper. With AF_XDP,
we want to register the memory model later on while configuring the ring
because we will know which memory model type to register
(MEM_TYPE_PAGE_SHARED or MEM_TYPE_XSK_BUFF_POOL).

The helpers igc_xdp_register_rxq_info() and igc_xdp_unregister_rxq_
info() are not useful anymore so they are removed.

Signed-off-by: Andre Guedes <andre.guedes@intel.com>
Signed-off-by: Vedang Patel <vedang.patel@intel.com>
Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>