HSI: ssi_protocol: fix potential resource leak in ssip_pn_open()

ssip_pn_open() claims the HSI client's port with hsi_claim_port(). When
hsi_register_port_event() gets some error and returns a negetive value,
the HSI client's port should be released with hsi_release_port().

Fix it by calling hsi_release_port() when hsi_register_port_event() fails.

Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>