hw/intc: Check @errp to handle the error of IOAPICCommonClass.realize()

hw/intc: Check @errp to handle the error of IOAPICCommonClass.realize()

IOAPICCommonClass implements its own private realize(), and this private
realize() allows error.

Since IOAPICCommonClass.realize() returns void, to check the error,
dereference @errp with ERRP_GUARD().

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Message-Id: <20240223085653.1255438-8-zhao1.liu@linux.intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>