ata: libahci_platform: Add of_node_put() before loop exit

Each iteration of for_each_child_of_node puts the previous node, but
in the case of a goto from the middle of the loop, there is no put,
thus causing a memory leak. Add an of_node_put before three such goto
statements.
Issue found with Coccinelle.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>