i2c: break out OF support into separate file

Also removes some ifdeffery.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index a6a90fe..189e0e6 100644
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -6,6 +6,7 @@
 obj-$(CONFIG_I2C)		+= i2c-core.o
 i2c-core-objs 			:= i2c-core-base.o i2c-core-smbus.o
 i2c-core-$(CONFIG_I2C_SLAVE) 	+= i2c-core-slave.o
+i2c-core-$(CONFIG_OF) 		+= i2c-core-of.o
 
 obj-$(CONFIG_I2C_SMBUS)		+= i2c-smbus.o
 obj-$(CONFIG_I2C_CHARDEV)	+= i2c-dev.o