media: bcm2835-unicam: Do not replace IRQ retcode during probe

platform_get_irq() cannot return the value 0. It will either return a non-zero
irq or a errcode.

If a errcode is returned, we need to populate the error code upwards. It will
give a more accurate reason of why it failed to the caller, who might decide
to retry later.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20240506-fix-broad-v2-1-e6a2a5c0d609@chromium.org
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>