dm: pinctrl: Add a function to parse PIN_CONFIG flags

Add a function which produces a flags word from a few common PIN_CONFIG
settings. This is useful for simple pinctrl drivers that don't need to worry
about drive strength, etc.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/pinctrl/pinctrl-uclass.c b/drivers/pinctrl/pinctrl-uclass.c
index c42b312..1acbfaf 100644
--- a/drivers/pinctrl/pinctrl-uclass.c
+++ b/drivers/pinctrl/pinctrl-uclass.c
@@ -15,6 +15,18 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
+int pinctrl_decode_pin_config(const void *blob, int node)
+{
+	int flags = 0;
+
+	if (fdtdec_get_bool(blob, node, "bias-pull-up"))
+		flags |= 1 << PIN_CONFIG_BIAS_PULL_UP;
+	else if (fdtdec_get_bool(blob, node, "bias-pull-down"))
+		flags |= 1 << PIN_CONFIG_BIAS_PULL_DOWN;
+
+	return flags;
+}
+
 #if CONFIG_IS_ENABLED(PINCTRL_FULL)
 /**
  * pinctrl_config_one() - apply pinctrl settings for a single node