[PATCH] PCI: fix sparse warning about pci_bus_flags

Sparse warns about casting to a __bitwise type.  However, it's correct
to do when defining the enum for pci_bus_flags_t, so add a __force to
quiet the warnings.  This will fix getting

    include/linux/pci.h:100:26: warning: cast to restricted type

from sparse all over the build.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>