octeontx2-af: Fix CGX Receive counters

Each CGX block supports 4 logical MACs (LMACS). Receive
counters CGX_CMR_RX_STAT0-8 are per LMAC and CGX_CMR_RX_STAT9-12
are per CGX.

Due a bug in previous patch, stale Per CGX counters values observed.

Fixes: 6620891 ("octeontx2-af: Support to retrieve CGX LMAC stats")
Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
Link: https://patch.msgid.link/20250513071554.728922-1-hkelam@marvell.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/marvell/octeontx2/af/cgx.c

@@ -717,6 +717,11 @@ int cgx_get_rx_stats(void *cgxd, int lmac_id, int idx, u64 *rx_stat)
 
 	if (!is_lmac_valid(cgx, lmac_id))
 		return -ENODEV;
+
+	/* pass lmac as 0 for CGX_CMR_RX_STAT9-12 */
+	if (idx >= CGX_RX_STAT_GLOBAL_INDEX)
+		lmac_id = 0;
+
 	*rx_stat =  cgx_read(cgx, lmac_id, CGXX_CMRX_RX_STAT0 + (idx * 8));
 	return 0;
 }