of/i2c: Generalize OF support

This patch cleans up the i2c OF support code to make it selectable by
all architectures and allow for automatic registration of i2c devices.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index 097f42a..80dd631 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -26,7 +26,7 @@
 
 config OF_I2C
 	def_tristate I2C
-	depends on (PPC_OF || MICROBLAZE) && I2C
+	depends on OF && !SPARC && I2C
 	help
 	  OpenFirmware I2C accessors