HSI: omap_ssi_core: fix unbalanced pm_runtime_disable()

In error label 'out1' path in ssi_probe(), the pm_runtime_enable()
has not been called yet, so pm_runtime_disable() is not needed.

Fixes: b209e047

 ("HSI: Introduce OMAP SSI driver")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>