net/mlx5e: xsk: Use xsk_buff_alloc_batch on striding RQ

XSK provides a function to allocate frames in batches for more efficient
processing. This commit starts using this function on striding RQ and
creates an optimized flow for XSK. A side effect is an opportunity to
optimize the regular RX flow by dropping branching for XSK cases.

Performance improvement is up to 6.4% in the aligned mode and up to 7.5%
in the unaligned mode.

Aligned mode, 2048-byte frames: 12.9 Mpps -> 13.8 Mpps
Aligned mode, 4096-byte frames: 11.8 Mpps -> 12.5 Mpps
Unaligned mode, 2048-byte frames: 11.9 Mpps -> 12.8 Mpps
Unaligned mode, 3072-byte frames: 11.4 Mpps -> 12.1 Mpps
Unaligned mode, 4096-byte frames: 11.0 Mpps -> 11.2 Mpps

CPU: Intel(R) Xeon(R) Gold 6240 CPU @ 2.60GHz

Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>