pci: remove explicit check to 64K ioport size

This check is useless, as bigger addresses will be ignored when
added to 'io' MemoryRegion, which has a size of 64K.

However, some architectures don't use the 'io' MemoryRegion, like
the alpha and versatile platforms. They create a PCI I/O region
bigger than 64K, so let them handle PCI I/O BARs in the higher range.

MST: reinstated work-around for BAR sizing.

Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
