i40e: use generic unrolled_count() macro

i40e: use generic unrolled_count() macro

i40e, as well as ice, has a custom loop unrolling macro for unrolling
Tx descriptors filling on XSk xmit.
Replace i40e defs with generic unrolled_count(), which is also more
convenient as it allows passing defines as its argument, not hardcoded
values, while the loop declaration will still be a usual for-loop.

Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://patch.msgid.link/20250206182630.3914318-3-aleksander.lobakin@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>