net/mlx5e: RX, Mind the MPWQE gaps when calculating offsets

Since cited patch, MLX5E_REQUIRED_WQE_MTTS is not a power of two.
Hence, usage of MLX5E_LOG_ALIGNED_MPWQE_PPW should be replaced,
as it lost some accuracy. Use the designated macro to calculate
the number of required MTTs.

This makes sure the solution in cited patch works properly.

While here, un-inline mlx5e_get_mpwqe_offset(), and remove the
unused RQ parameter.

Fixes: c3c94023 ("net/mlx5e: Add resiliency in Striding RQ mode for packets larger than MTU")
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>