net/mlx5: check delay drop settings in kernel driver

net/mlx5: check delay drop settings in kernel driver

The delay drop is the common feature managed on per device basis
and the kernel driver is responsible one for the initialization and
rearming.

By default, the timeout value is set to activate the delay drop when
the driver is loaded.

A private flag "dropless_rq" is used to control the rearming. Only
when it is on, the rearming will be handled once received a timeout
event. Or else, the delay drop will be deactivated after the first
timeout occurs and all the Rx queues won't have this feature.

The PMD is trying to query this flag and warn the application when
some queues are created with delay drop but the flag is off.

Signed-off-by: Bing Zhao <bingz@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>