vfio/pci: Make vfio_pci_relocate_msix() and vfio_msix_early_setup() return a bool

vfio/pci: Make vfio_pci_relocate_msix() and vfio_msix_early_setup() return a bool

Since vfio_pci_relocate_msix() and vfio_msix_early_setup() takes
an 'Error **' argument, best practices suggest to return a bool.
See the qapi/error.h Rules section.

By this chance, pass errp directly to vfio_msix_early_setup() to avoid
calling error_propagate().

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>