pci: Align PCI addresses on BAR size boundary

PCI I/O and Memory must be allocated to a device in a naturally
aligned way. For example, if a device asks for 0xB0 of PCI I/O
space then it must be aligned on an address that is a multiple
of 0xB0 (http://www.tldp.org/LDP/tlk/dd/pci.html

)

Cc: Thomas Huth <thuth@redhat.com>
Cc: Andrew Jones <drjones@redhat.com>
Reported-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>