i2c: Migration aids for i2c_adapter.dev removal

Flag i2c_adapter.dev for removal after userspace tools get upgraded, and
include a near-term code migration aid to facilitate this:

 - The class device gets the name attribute it should have had.  This
   was previously (wrongly) associated with the i2c_adapter.dev node.
   Sysfs based tools and libraries can start converting right away.

 - Issue a warning for legacy adapter drivers that don't provide any
   physical device node; so systems with those drivers will know to
   fix this problem earlier.

This is one of a series of patches to help the I2C stack become a better
citizen of the Linux Driver Model world.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

Documentation/feature-removal-schedule.txt

@@ -226,6 +226,23 @@ Who:	Jean Delvare <khali@linux-fr.org>
 
 ---------------------------
 
+What:	i2c_adapter.dev
+	i2c_adapter.list
+When:	July 2007
+Why:	Superfluous, given i2c_adapter.class_dev:
+	  * The "dev" was a stand-in for the physical device node that legacy
+	    drivers would not have; but now it's almost always present.  Any
+	    remaining legacy drivers must upgrade (they now trigger warnings).
+	  * The "list" duplicates class device children.
+	The delay in removing this is so upgraded lm_sensors and libsensors
+	can get deployed.  (Removal causes minor changes in the sysfs layout,
+	notably the location of the adapter type name and parenting the i2c
+	client hardware directly from their controller.)
+Who:	Jean Delvare <khali@linux-fr.org>,
+	David Brownell <dbrownell@users.sourceforge.net>
+
+---------------------------
+
 What:	IPv4 only connection tracking/NAT/helpers
 When:	2.6.22
 Why:	The new layer 3 independant connection tracking replaces the old