RDMA/bnxt_re: Fix incorrect BAR check in bnxt_qplib_map_creq_db()

RCFW_COMM_CONS_PCI_BAR_REGION is defined as BAR 2, so checking
!creq_db->reg.bar_id is incorrect and always false.

pci_resource_start() returns the BAR base address, and a value of 0
indicates that the BAR is unassigned. Update the condition to test
bar_base == 0 instead.

This ensures the driver detects and logs an error for an unassigned
RCFW communication BAR.

Fixes: cee0c7b ("RDMA/bnxt_re: Refactor command queue management code")
Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Link: https://patch.msgid.link/20251217100158.752504-1-alok.a.tiwari@oracle.com
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>

Author: aloktiwa

drivers/infiniband/hw/bnxt_re/qplib_rcfw.c

@@ -1112,7 +1112,7 @@ static int bnxt_qplib_map_creq_db(struct bnxt_qplib_rcfw *rcfw, u32 reg_offt)
 	creq_db->dbinfo.flags = 0;
 	creq_db->reg.bar_id = RCFW_COMM_CONS_PCI_BAR_REGION;
 	creq_db->reg.bar_base = pci_resource_start(pdev, creq_db->reg.bar_id);
-	if (!creq_db->reg.bar_id)
+	if (!creq_db->reg.bar_base)
 		dev_err(&pdev->dev,
 			"QPLIB: CREQ BAR region %d resc start is 0!",
 			creq_db->reg.bar_id);