vfio/fsl-mc: Implement VFIO_DEVICE_GET_INFO ioctl

Allow userspace to get fsl-mc device info (number of regions
and irqs).

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@nxp.com>
Signed-off-by: Diana Craciun <diana.craciun@oss.nxp.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>