dma: ti: k3-udma: Fix ring_idx to pair k3 nav rings

ring_idx was not correctly assigned in case of tflow_id is zero.
Which leads to wrong pairing of DMA for drivers like OSPI.

Fixes: 4312a1dfca26 ("dma: ti: k3-udma: Use ring_idx to pair k3 nav rings")
Reviewed-by: Jai Luthra <j-luthra@ti.com>
Signed-off-by: Udit Kumar <u-kumar1@ti.com>
diff --git a/drivers/dma/ti/k3-udma.c b/drivers/dma/ti/k3-udma.c
index ed0a9bf..ef3074a 100644
--- a/drivers/dma/ti/k3-udma.c
+++ b/drivers/dma/ti/k3-udma.c
@@ -884,10 +884,10 @@
 		return ret;
 
 	tchan = uc->tchan;
-	if (tchan->tflow_id >= 0)
+	if (tchan->tflow_id > 0)
 		ring_idx = tchan->tflow_id;
 	else
-		ring_idx = ud->bchan_cnt + tchan->id;
+		ring_idx = tchan->id;
 
 	ret = k3_nav_ringacc_request_rings_pair(ud->ringacc, ring_idx, -1,
 						&uc->tchan->t_ring,