usb: typec: Fix unchecked return value

Currently there is no check on platform_get_irq() return value
in case it fails, hence never actually reporting any errors and
causing unexpected behavior when using such value as argument
for function regmap_irq_get_virq().

Fix this by adding a proper check, a message error and return
*irq* in case platform_get_irq() fails.

Addresses-Coverity-ID: 1443899 ("Improper use of negative value")
Fixes: d2061f9c ("usb: typec: add driver for Intel Whiskey Cove PMIC USB Type-C PHY")
Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>