tests/libqos/pci-pc: Fix qpci_pc_iomap() to map BARs aligned

qpci_pc_iomap() maps BARs one after the other, without padding.  This
is wrong.  PCI Local Bus Specification Revision 3.0, 6.2.5.1. Address
Maps: "all address spaces used are a power of two in size and are
naturally aligned".  That's because the size of a BAR is given by the
number of address bits the device decodes, and the BAR needs to be
mapped at a multiple of that size to ensure the address decoding
works.

Fix qpci_pc_iomap() accordingly.  This takes care of a FIXME in
ivshmem-test.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1458066895-20632-7-git-send-email-armbru@redhat.com>