of: Drop full path from full_name for PDT systems

Now that there are no more users of path_component_name for Sparc
outside of the PDT code and all users of device_node.full_name are
converted to use "%pOF" printf specifier, we can align Sparc with FDT
and store just the base node name and unit address in full_name. This
makes path_component_name redundant, so it can be removed.

As full_name is used by printf specifiers, set it as early as possible.

Cc: Frank Rowand <frowand.list@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>