driver: base: pinctrl: return error from pinctrl_bind_pins()

strict pin controller returns -EINVAL in case of pin request which
is already claimed by somebody else.
Following is the sequence of calling pin_request() from
pinctrl_bind_pins():-
pinctrl_bind_pins()->pinctrl_select_state()->pinmux_enable_setting()->
pin_request()

But pinctrl_bind_pins() only returns -EPROBE_DEFER which makes device
driver probe successful even if the pin request is rejected by the pin
controller subsystem.

This commit modifies pinctrl_bind_pins() to return error if the pin is
rejected by pin control subsystem.
Signed-off-by: Deepak Das <deepak_das@mentor.com>
[Rewrote to be cleaner]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/base/pinctrl.c

@@ -91,9 +91,13 @@ int pinctrl_bind_pins(struct device *dev)
 	devm_kfree(dev, dev->pins);
 	dev->pins = NULL;
 
-	/* Only return deferrals */
-	if (ret != -EPROBE_DEFER)
-		ret = 0;
-
+	/* Return deferrals */
+	if (ret == -EPROBE_DEFER)
+		return ret;
+	/* Return serious errors */
+	if (ret == -EINVAL)
 		return ret;
+	/* We ignore errors like -ENOENT meaning no pinctrl state */
+
+	return 0;
 }