vboot: Pass vb2 context and use vboot2 NV routines

Passing the vb2 context around allows using more of the vb2 functions in
future changes, and prepares for a future where we directly use the
context as it was set up in firmware verification.

TEST=make runtests; emerge-kevin coreboot depthcharge

Change-Id: I8efa606dbdec5d195b66eb899e76fdc84337ad36
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/404997
Reviewed-by: Shelley Chen <shchen@chromium.org>
17 files changed