ata: sata_highbank: fix OF node reference leak in highbank_initialize_phys()

The OF node reference obtained by of_parse_phandle_with_args() is not
released on early return. Add a of_node_put() call before returning.

Fixes: 8996b89d ("ata: add platform driver for Calxeda AHCI controller")
Signed-off-by: Joe Hattori <joe@pf.is.s.u-tokyo.ac.jp>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>