data/data/aws/vpc: Drop 'current' from aws_region
data/data/aws/vpc: Drop 'current' from aws_region

It's the default.  The old parameter was deprecated before
terraform-providers/terraform-provider-aws@1cc81c92
(docs/data-source/aws_region: Remove now deprecated current argument,
2018-02-09, v1.9.0), and we're pinning 1.39.0 since ac5aeed6
(data/aws: bump aws provider, 2018-11-01, #594).  Changing this
avoids:

  $ openshift-install --log-level=debug create cluster
  ...
  - Downloading plugin for provider "aws" (1.39.0)...
  ...
  Warning: module.vpc.data.aws_region.current: "current": [DEPRECATED] Defaults to current provider region if no other filtering is enabled
  ...

derekhiggins/installer,derekhiggins/installer