Remove sync requirements of pci device trait
Remove sync requirements of pci device trait

It's not needed.

BUG=chromium:831850
TEST=cargo test

Change-Id: I7e38590271ec14db422f5f3421302e98a2ca19ab
Reviewed-on: https://chromium-review.googlesource.com/1194317
Commit-Ready: Jingkui Wang <c645f91f31b7cead6dc73127db4670945d892e95@google.com>
Tested-by: Jingkui Wang <c645f91f31b7cead6dc73127db4670945d892e95@google.com>
Reviewed-by: Dylan Reid <c791bfe44996c1eed9c7149a0c5f12a86d58eb85@chromium.org>

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