Revert "sparc: Convert to using %pOFn instead of device_node.name"

This reverts commit 0b9871a3.

Causes crashes with qemu, interacts badly with commit commit
6d0a70a2

 ("vsprintf: print OF node name using full_name")
etc.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>