phy: renesas: phy-rcar-gen2: Fix the array off by one warning

Fix the below smatch warning by adding variable check rather than the
hardcoded value.
warn: array off by one? 'data->select_value[channel_num]'

Reported-by: Dan Carpenter <[e-mail]>
Signed-off-by: Biju Das <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>
Reviewed-by: Wolfram Sang <[e-mail]>
Reviewed-by: Ulrich Hecht <[e-mail]>
Reviewed-by: Yoshihiro Shimoda <[e-mail]>
Signed-off-by: Kishon Vijay Abraham I <[e-mail]>

drivers/phy/renesas/phy-rcar-gen2.c

···
 struct rcar_gen2_phy_data {
 	const struct phy_ops *gen2_phy_ops;
 	const u32 (*select_value)[PHYS_PER_CHANNEL];
+	const u32 num_channels;
 };
 
 static int rcar_gen2_phy_init(struct phy *p)
···
 static const struct rcar_gen2_phy_data rcar_gen2_usb_phy_data = {
 	.gen2_phy_ops = &rcar_gen2_phy_ops,
 	.select_value = pci_select_value,
+	.num_channels = ARRAY_SIZE(pci_select_value),
 };
 
 static const struct rcar_gen2_phy_data rz_g1c_usb_phy_data = {
 	.gen2_phy_ops = &rz_g1c_phy_ops,
 	.select_value = usb20_select_value,
+	.num_channels = ARRAY_SIZE(usb20_select_value),
 };
 
 static const struct of_device_id rcar_gen2_phy_match_table[] = {
···
 		channel->selected_phy = -1;
 
 		error = of_property_read_u32(np, "reg", &channel_num);
-		if (error || channel_num > 2) {
+		if (error || channel_num >= data->num_channels) {
 			dev_err(dev, "Invalid \"reg\" property\n");
 			of_node_put(np);
 			return error;