pinctrl-snapdragon: Get rid of custom drive-strength values

Use standard pinconf drive-strength values from Linux DT bindings rather
than ones based on custom u-boot header. These changes are in direction
to make u-boot DTs for Qcom SoCs to be compatible with standard Linux
DT bindings.

Also, add support for pinconf bias-pull-up.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
diff --git a/arch/arm/dts/dragonboard820c.dts b/arch/arm/dts/dragonboard820c.dts
index aaca681..ad201d4 100644
--- a/arch/arm/dts/dragonboard820c.dts
+++ b/arch/arm/dts/dragonboard820c.dts
@@ -8,7 +8,6 @@
 /dts-v1/;
 
 #include "skeleton64.dtsi"
-#include <dt-bindings/pinctrl/pinctrl-snapdragon.h>
 
 / {
 	model = "Qualcomm Technologies, Inc. DB820c";
@@ -71,7 +70,7 @@
 			blsp8_uart: uart {
 				function = "blsp_uart8";
 				pins = "GPIO_4", "GPIO_5";
-				drive-strength = <DRIVE_STRENGTH_8MA>;
+				drive-strength = <8>;
 				bias-disable;
 			};
 		};