crosvm: use anyhow context in device helpers
crosvm: use anyhow context in device helpers

Use anyhow context consistently rather than logging with error!()
inside the helper functions.

BUG=None
TEST=Run crosvm twice with the same VVU socket name

Change-Id: Idadd4a65f5ce6188e9623b3311842e2f90eb4916
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3739586
Reviewed-by: Junichi Uekawa <6bd240a6ce32463e272bb69c685a8e946b33ac05@chromium.org>
Reviewed-by: Keiichi Watanabe <815e4e8f7c92a23424d7c3f51ead622bcedbc720@chromium.org>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Commit-Queue: Daniel Verkamp <72bc170b46ec491f7bdd4359a1c0bfed274de40c@chromium.org>

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