i2c: Provide compatibility links for i2c adapters

Some user-space applications may be relying on i2c adapters showing up
as class devices in sysfs. Provide compatibility links for them for
the time being. We will remove them after a long transition period.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 711ca08..d7ece13 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -27,6 +27,14 @@
 	boolean
 	default y
 
+config I2C_COMPAT
+	boolean "Enable compatibility bits for old user-space"
+	default y
+	help
+	  Say Y here if you intend to run lm-sensors 3.1.1 or older, or any
+	  other user-space package which expects i2c adapters to be class
+	  devices. If you don't know, say Y.
+
 config I2C_CHARDEV
 	tristate "I2C device interface"
 	help