bnxt_en: Fix inconsistent BNXT_FLAG_AGG_RINGS logic.

If there aren't enough RX rings available, the driver will attempt to
use a single RX ring without the aggregation ring.  If that also
fails, the BNXT_FLAG_AGG_RINGS flag is cleared but the other ring
parameters are not set consistently to reflect that.  If more RX
rings become available at the next open, the RX rings will be in
an inconsistent state and may crash when freeing the RX rings.

Fix it by restoring the BNXT_FLAG_AGG_RINGS if not enough RX rings are
available to run without aggregation rings.

Fixes: bdbd1eb59c56 ("bnxt_en: Handle no aggregation ring gracefully.")
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -8520,8 +8520,11 @@ static int bnxt_get_dflt_rings(struct bnxt *bp, int *max_rx, int *max_tx,
 		/* Not enough rings, try disabling agg rings. */
 		bp->flags &= ~BNXT_FLAG_AGG_RINGS;
 		rc = bnxt_get_max_rings(bp, max_rx, max_tx, shared);
-		if (rc)
+		if (rc) {
+			/* set BNXT_FLAG_AGG_RINGS back for consistency */
+			bp->flags |= BNXT_FLAG_AGG_RINGS;
 			return rc;
+		}
 		bp->flags |= BNXT_FLAG_NO_AGG_RINGS;
 		bp->dev->hw_features &= ~(NETIF_F_LRO | NETIF_F_GRO_HW);
 		bp->dev->features &= ~(NETIF_F_LRO | NETIF_F_GRO_HW);