Remove creation time checks.

We should not be relying on the HAL service to add CREATION_TIME to
keys.  It was always intended to be an optional tag that could be
added by keystore, or maybe the caller of keystore.  One widespread
Keymaster implementation started adding it (somewhat erroneously) if
it wasn't provided, and it appears that this implementation's behavior
became assumed to be the required behavior.

Test: VtsHalKeymasterV4_0TargetTest
Change-Id: I34267c4e1f59fd8ee5f898f8c746a7b49f4d74a5