vfio/pci: Free leaked timer in vfio_realize error path

vfio/pci: Free leaked timer in vfio_realize error path

When vfio_realize fails, the mmap_timer used for INTx optimization
isn't freed. As this timer isn't activated yet, the potential impact
is just a piece of leaked memory.

Fixes: ea486926b07d ("vfio-pci: Update slow path INTx algorithm timer related")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>