kvm tools: Fix PCI masking on probes

This patch adds a missing check of mask during probing of PCI BARs.

The missing check manifested in wrong address values for the BARs after the
initial probe.

Reported-by: David Evensky <evensky@dancer.ca.sandia.gov>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>