vdpa/mlx5: Distribute RX virtqueues in RQT object

vdpa/mlx5: Distribute RX virtqueues in RQT object

Distribute the available rx virtqueues amongst the available RQT
entries.

RQTs require to have a power of two entries. When creating or modifying
the RQT, use the lowest number of power of two entries that is not less
than the number of rx virtqueues. Distribute them in the available
entries such that some virtqueus may be referenced twice.

This allows to configure any number of virtqueue pairs when multiqueue
is used.

Reviewed-by: Si-Wei Liu <si-wei.liu@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eli Cohen <elic@nvidia.com>
Link: https://lore.kernel.org/r/20220105114646.577224-3-elic@nvidia.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>