net/ena: check memory BAR before initializing LLQ

net/ena: check memory BAR before initializing LLQ

The ena_com_config_dev_mode() performs many calculations related to LLQ
and then performs an admin queue call to configure LLQ in the device.

All of the operations performed by ena_com_config_dev_mode() are
unnecessary if membar hasn't been found. Move the dev_mem_base check
before ena_com_config_dev_mode() call. This prevents the unnecessary
operations from being performed.

Fixes: 2fca2a98c0d1 ("net/ena: support LLQv2")
Cc: stable@dpdk.org
Signed-off-by: Dawid Gorecki <dgr@semihalf.com>
Reviewed-by: Michal Krawczyk <mk@semihalf.com>
Reviewed-by: Shai Brandes <shaibran@amazon.com>