pinctrl: fix build when CONFIG_OF && !CONFIG_PINCTRL

pinctrl/devicetree.c won't compile when !CONFIG_PINCTRL, since the
pinctrl headers don't declare some types when !PINCTRL. Make sure
pinctrl/Makefile only attempts to compile devicetree.c when OF &&
PINCTRL.
Acked-by: Dong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/Makefile

@@ -5,7 +5,9 @@ ccflags-$(CONFIG_DEBUG_PINCTRL)	+= -DDEBUG
 obj-$(CONFIG_PINCTRL)		+= core.o
 obj-$(CONFIG_PINMUX)		+= pinmux.o
 obj-$(CONFIG_PINCONF)		+= pinconf.o
-obj-$(CONFIG_OF)		+= devicetree.o
+ifeq ($(CONFIG_OF),y)
+obj-$(CONFIG_PINCTRL)		+= devicetree.o
+endif
 obj-$(CONFIG_GENERIC_PINCONF)	+= pinconf-generic.o
 obj-$(CONFIG_PINCTRL_PXA3xx)	+= pinctrl-pxa3xx.o
 obj-$(CONFIG_PINCTRL_MMP2)	+= pinctrl-mmp2.o