pci-bridge: Set limit smaller than base at initialize
pci-bridge: Set limit smaller than base at initialize

According to pci bridge spec, the io/mem/prefetch mem limit register
must be programmed to a smaller value than the corresponding base register
if there is no io/mem/prefetch mem on the secondary side of the brige.

When bridge is created, it doesn't have any child device, then
no io/mem/prefetch mem on the secondary side of the bridge, so this
patch set limit to 0, but base to 0xffff.

When a device is attached behind the bridge, kernel will assign
resource and set the right value to these base and limit register.

BUG=b:199442120
BUG=b:185084350
TEST=crosvm run --bios OVMF.fd
TEST=hotplug in/out a pcie device to pcie root port repeatly

Change-Id: Id1c2ff1132d59e1aafd548fc17ab5aee2023dd8c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3166883
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Daniel Verkamp <72bc170b46ec491f7bdd4359a1c0bfed274de40c@chromium.org>
Commit-Queue: Daniel Verkamp <72bc170b46ec491f7bdd4359a1c0bfed274de40c@chromium.org>

google/crosvm,google/crosvm,google/crosvm,google/crosvm