pinctrl: qcom: add support for bias-pull-down

Add support for bias-pull-down as an alternate of bias-pull-up.

Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
diff --git a/drivers/pinctrl/qcom/pinctrl-qcom.c b/drivers/pinctrl/qcom/pinctrl-qcom.c
index 3c3336e..4f4e9a8 100644
--- a/drivers/pinctrl/qcom/pinctrl-qcom.c
+++ b/drivers/pinctrl/qcom/pinctrl-qcom.c
@@ -44,6 +44,7 @@
 	{ "drive-strength", PIN_CONFIG_DRIVE_STRENGTH, 2 },
 	{ "bias-disable", PIN_CONFIG_BIAS_DISABLE, 0 },
 	{ "bias-pull-up", PIN_CONFIG_BIAS_PULL_UP, 3 },
+	{ "bias-pull-down", PIN_CONFIG_BIAS_PULL_UP, 1 },
 	{ "output-high", PIN_CONFIG_OUTPUT, 1, },
 	{ "output-low", PIN_CONFIG_OUTPUT, 0, },
 };