Input: cpcap-pwrbutton - handle errors from platform_get_irq()

The function cpcap_power_button_probe() does not perform
sufficient error checking after executing platform_get_irq(),
thus fix it.

Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
Link: https://lore.kernel.org/r/20210802121740.8700-1-tangbin@cmss.chinamobile.com


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>