of: remove /proc/device-tree

The same data is now available in sysfs, so we can remove the code
that exports it in /proc and replace it with a symlink to the sysfs
version.

Tested on versatile qemu model and mpc5200 eval board. More testing
would be appreciated.

v5: Fixed up conflicts with mainline changes

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Cc: Pantelis Antoniou <panto@antoniou-consulting.com>

fs/proc/root.c

@@ -183,9 +183,6 @@ void __init proc_root_init(void)
 	proc_mkdir("openprom", NULL);
 #endif
 	proc_tty_init();
-#ifdef CONFIG_PROC_DEVICETREE
-	proc_device_tree_init();
-#endif
 	proc_mkdir("bus", NULL);
 	proc_sys_init();
 }