net/mlx5e: Optimize RQ page deallocation

mlx5e_free_rx_mpwqe loops over all pages of a MPWQE, calling
mlx5e_page_release for ones that are not scheduled for XDP_TX or
XDP_REDIRECT; and mlx5e_page_release checks whether it's an XSK RQ or a
regular one for each page/XSK frame. This check can be moved outside the
loop to reduce the number of branches.

mlx5e_free_rx_wqe loops over all fragments, calling mlx5e_page_release
for the ones that are last in a page; and mlx5e_page_release checks
whether it's an XSK RQ or a regular one for each fragment. Using the
fact that XSK doesn't support multiple fragments, it can be optimized
for both XSK and regular usages:

1. Make an early check for XSK and call its deallocator directly, saving
3 branches (loop condition, frag->last_in_page and selection of
deallocator).

2. Call the regular deallocator directly in the non-XSK case, saving a
branch per fragment, except the first one.

After the changes, mlx5e_page_release is removed, as there are no
callers left.

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>