brillo_sdk: Remove --sdk-dir option.

The --sdk-dir option was only semi-functional and created a confusing
user experience. For now we've decided that this option is unnecessary,
so we're removing it entirely.

SDKs now always live in /chromite/sdk_checkouts and `brillo sdk` is
only functional inside a workspace.

BUG=brillo:910
TEST=cbuildbot/run_tests
TEST=brillo sdk
TEST=brillo sdk --version
TEST=brillo sdk --update latest
TEST=brillo sdk --update tot

Change-Id: I10cdede7a97f4b41daa842f039ff3ade0657f73d
Reviewed-on: https://chromium-review.googlesource.com/266906
Reviewed-by: David Pursell <dpursell@chromium.org>
Tested-by: David Pursell <dpursell@chromium.org>
Commit-Queue: David Pursell <dpursell@chromium.org>
2 files changed