ice: xsk: drop power of 2 ring size restriction for AF_XDP

We had multiple customers in the past months that reported commit
296f13ff ("ice: xsk: Force rings to be sized to power of 2")
makes them unable to use ring size of 8160 in conjunction with AF_XDP.
Remove this restriction.

Fixes: 296f13ff

 ("ice: xsk: Force rings to be sized to power of 2")
CC: Alasdair McWilliam <alasdair.mcwilliam@outlook.com>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Tested-by: George Kuruvinakunnel <george.kuruvinakunnel@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>