Setup vold_key keystore2_key namespace.

Allow vold to access its namespace using raw Keymint blobs.

Test: keystore2_test runs some tests against this policy.
Bug: 160623310
Bug: 158500146
Change-Id: Iaf338f1ac48dd56ef6e1b73cb3b8634a91e8bf9f
Merged-In: Iaf338f1ac48dd56ef6e1b73cb3b8634a91e8bf9f
3 files changed