Changes for Vts related to Strongbox. Strongbox is only required to supports...

Changes for Vts related to Strongbox. Strongbox is only required to supports 2048 bit keys and optionally required to support Device Unique Attestations.
Test: atest VtsHalKeymasterV4_0TargetTest and atest VtsHalKeymasterV4_1TargetTest.
Bug: Related to b/150122447.

Signed-off-by: Chirag Pathak <pathakc@google.com>
Change-Id: I46993aff322dff12af4ce88a46c00316f14f3227