ia64: Fix resource assignment for root busses

ia64 was assigning resources to root busses after allocations had
been made for child busses.  Calling pcibios_setup_root_windows() from
pcibios_fixup_bus() solves this problem by assigning the resources to
the root bus before child busses are scanned.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Tested-by: Andrew Patterson <andrew.patterson@hp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>