Use SoftKeymasterDevice::keymaster_device rather than casting.

Also document that SoftKeymasterDevice should not be freed.

Change-Id: I027f137b0ffd474bb4b429691fe87eef6338b723
(cherry picked from commit 47a79ffad8333120870cb613fa4e75990b073026)
1 file changed
tree: 36e20446a1d1809f2944fdc856925174fd899d87
  1. keystore/
  2. keystore-engine/
  3. softkeymaster/