net/enic: Allow at least 8 RQs to always be used

Enic started using netif_get_num_default_rss_queues() to set the number
of RQs used in commit cc94d6c4 ("enic: Adjust used MSI-X
wq/rq/cq/interrupt resources in a more robust way")

This resulted in machines with less than 16 cpus using less than 8 RQs.
Allow enic to use at least 8 RQs no matter how many cpus are in the
machine to not impact existing enic workloads after a kernel upgrade.

Reviewed-by: John Daley <johndale@cisco.com>
Reviewed-by: Satish Kharat <satishkh@cisco.com>
Signed-off-by: Nelson Escobar <neescoba@cisco.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Link: https://patch.msgid.link/20250521-enic_min_8rq-v1-1-691bd2353273@cisco.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>