pci: avoid accessing slot_reserved_mask directly outside of pci.c

pci: avoid accessing slot_reserved_mask directly outside of pci.c

This patch provides accessor functions as replacements for direct
access to slot_reserved_mask according to the comment at the top
of include/hw/pci/pci_bus.h which advises that data structures for
PCIBus should not be directly accessed but instead be accessed using
accessor functions in pci.h.

Three accessor functions can conveniently replace all direct accesses
of slot_reserved_mask. With this patch, the new accessor functions are
used in hw/sparc64/sun4u.c and hw/xen/xen_pt.c and pci_bus.h is removed
from the included header files of the same two files.

No functional change intended.

Signed-off-by: Chuck Zmudzinski <brchuckz@aol.com>
Message-Id: <b1b7f134883cbc83e455abbe5ee225c71aa0e8d0.1678888385.git.brchuckz@aol.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> [sun4u]