When allocating memory for the vfio_irq_info parameter of the
VFIO_DEVICE_GET_IRQ_INFO ioctl, we used the wrong size. Let's
fix it by using the right size.

Reviewed-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Jing Zhang <bjzhjing@linux.vnet.ibm.com>
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Message-Id: <20170718014926.44781-2-bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>