net: phy: microchip: add comments for the modified LAN88xx phy ID mask.

add comments for the updated LAN88xx phy ID mask in the previous patch.
Signed-off-by: NYuiko Oshino <yuiko.oshino@microchip.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

drivers/net/phy/microchip.c

@@ -345,6 +345,10 @@ static int lan88xx_config_aneg(struct phy_device *phydev)
 static struct phy_driver microchip_phy_driver[] = {
 {
 	.phy_id		= 0x0007c132,
+	/* This mask (0xfffffff2) is to differentiate from
+	 * LAN8742 (phy_id 0x0007c130 and 0x0007c131)
+	 * and allows future phy_id revisions.
+	 */
 	.phy_id_mask	= 0xfffffff2,
 	.name		= "Microchip LAN88xx",