pinctrl: make pinctrl_register() return proper error code

Currently, pinctrl_register() just returns NULL on error, so the
callers can not know the exact reason of the failure.

Some of the pinctrl drivers return -EINVAL, some -ENODEV, and some
-ENOMEM on error of pinctrl_register(), although the error code
might be different from the real cause of the error.

This commit reworks pinctrl_register() to return the appropriate
error code and modifies all of the pinctrl drivers to use IS_ERR()
for the error checking and PTR_ERR() for getting the error code.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Patrice Chotard <patrice.chotard@st.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Lee Jones <lee@kernel.org>
Acked-by: Sören Brinkmann <soren.brinkmann@xilinx.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Ray Jui <rjui@broadcom.com>
Acked-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Acked-by: Hongzhou Yang <hongzhou.yang@mediatek.com>
Acked-by: Wei Chen <Wei.Chen@csr.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/pinctrl/pinctrl-amd.c b/drivers/pinctrl/pinctrl-amd.c
index e7479125..d8e3f7c 100644
--- a/drivers/pinctrl/pinctrl-amd.c
+++ b/drivers/pinctrl/pinctrl-amd.c
@@ -789,9 +789,9 @@
 	amd_pinctrl_desc.name = dev_name(&pdev->dev);
 	gpio_dev->pctrl = pinctrl_register(&amd_pinctrl_desc,
 					&pdev->dev, gpio_dev);
-	if (!gpio_dev->pctrl) {
+	if (IS_ERR(gpio_dev->pctrl)) {
 		dev_err(&pdev->dev, "Couldn't register pinctrl driver\n");
-		return -ENODEV;
+		return PTR_ERR(gpio_dev->pctrl);
 	}
 
 	ret = gpiochip_add(&gpio_dev->gc);