[ Merge of http://go/wvgerrit/149849 ]
With ECC based DRM cert, the session key is expected to be 32, as
compared to 16 bytes in RSA case. This CL adds supports for 32 bytes
session key.
Bug: 236317198
Test: oemcrypto_test
Change-Id: I657fdd92d17736a23375ddcd457f83efa6ca6d1f