net/mlx5e: RX, Change wqe last_in_page field from bool to bit flags

Change the bool flag to a bitfield as we'll use it in a downstream patch
in the series to add signaling about skipping a fragment release.

Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>