hw/pci: Fix typo in PCI hot-plug error message

'occupied' is spelled like 'ocuppied' in the message.

Signed-off-by: Julia Suvorova <jusual@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20201006133958.600932-1-jusual@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>