net/mlx5: fix allocation size of RQT attribute

net/mlx5: fix allocation size of RQT attribute

The receive queues list size is based on the size of uint32_t, so
when allocating the memory, the correct value should be used. Or
else there is risk to corrupt the memory, depending on the queues
number, because there is some pad area for alignment. If the queue
number is not large enough, the issue couldn't be observed.

Fixes: dc9ceff73c99 ("net/mlx5: create advanced RxQ via DevX")
Cc: stable@dpdk.org
Signed-off-by: Ori Kam <orika@mellanox.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>