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 cc94d6c ("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>

Author: nrescobar

drivers/net/ethernet/cisco/enic/enic.h

@@ -26,6 +26,7 @@
 
 #define ENIC_WQ_MAX		256
 #define ENIC_RQ_MAX		256
+#define ENIC_RQ_MIN_DEFAULT	8
 
 #define ENIC_WQ_NAPI_BUDGET	256
 

drivers/net/ethernet/cisco/enic/enic_main.c

@@ -2296,7 +2296,8 @@ static int enic_adjust_resources(struct enic *enic)
 		 * used based on which resource is the most constrained
 		 */
 		wq_avail = min(enic->wq_avail, ENIC_WQ_MAX);
-		rq_default = netif_get_num_default_rss_queues();
+		rq_default = max(netif_get_num_default_rss_queues(),
+				 ENIC_RQ_MIN_DEFAULT);
 		rq_avail = min3(enic->rq_avail, ENIC_RQ_MAX, rq_default);
 		max_queues = min(enic->cq_avail,
 				 enic->intr_avail - ENIC_MSIX_RESERVED_INTR);