Docs: return EARLY_BOOT_ENDED instead of INVALID_KEY_BLOB.

All attempts to use an EARLY_BOOT_ONLY key after earlyBootEnded()
is called must fail with Error::EARLY_BOOT_ENDED.

Test: run vts -m VtsAidlKeyMintTarget
Change-Id: Ic3d028ceb7f71e6e266993ec4e877770cd8e5c4a
1 file changed