staging: typec: fusb302: Use client->irq as irq if set

The fusb302 is also used on x86 systems where the platform code sets
the irq in client->irq and there is no gpio named fcs,int_n.

Cc: "Yueyao (Nathan) Zhu" <yueyao@google.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>