usb: ohci-s3c2410: Use platform_get_irq() to get the interrupt

Accessing platform device resources directly has long been deprecated for
DT as IRQ resources may not be available at device creation time. Drivers
relying on the static IRQ resources is blocking removing the static setup
from the DT core code.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211215225358.1993774-1-robh@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>