pinctrl: tegra: xusb: Add note about legacy status

Add a comment about why the call to of_match_node() cannot be replaced
by of_device_get_match_data(). This will hopefully prevent people from
attempting to clean this up in the future.

Signed-off-by: Thierry Reding <[e-mail]>
Link: https://lore.kernel.org/r/20190923095400.GA11084@ulmo
Signed-off-by: Linus Walleij <[e-mail]>

drivers/pinctrl/tegra/pinctrl-tegra-xusb.c

···
 	mutex_init(&padctl->lock);
 	padctl->dev = &pdev->dev;
 
+	/*
+	 * Note that we can't replace this by of_device_get_match_data()
+	 * because we need the separate matching table for this legacy code on
+	 * Tegra124. of_device_get_match_data() would attempt to use the table
+	 * from the updated driver and fail.
+	 */
 	match = of_match_node(tegra_xusb_padctl_of_match, pdev->dev.of_node);
 	padctl->soc = match->data;