net: dsa: bcm_sf2: Update compatible string for 7278B0

Update the compatible string and Device Tree binding document for
7278B0.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/dsa/bcm_sf2.c b/drivers/net/dsa/bcm_sf2.c
index 8ea0cd4..0378ede 100644
--- a/drivers/net/dsa/bcm_sf2.c
+++ b/drivers/net/dsa/bcm_sf2.c
@@ -948,6 +948,9 @@ static const struct of_device_id bcm_sf2_of_match[] = {
 	{ .compatible = "brcm,bcm7278-switch-v4.0",
 	  .data = &bcm_sf2_7278_data
 	},
+	{ .compatible = "brcm,bcm7278-switch-v4.8",
+	  .data = &bcm_sf2_7278_data
+	},
 	{ /* sentinel */ },
 };
 MODULE_DEVICE_TABLE(of, bcm_sf2_of_match);