[ Merge of http://go/wvgerrit/148469 ]
OEMCrypto_GetOEMPublicCertificate needed to be called
before the OEM private key was loaded due to a bug in OEMCrypto.
The bug has been addressed and the call can now be removed.
OEMCrypto_GetOEMPublicCertificate is only applicable to
devices with OEM certs as their root of trust. Devices with
keyboxes (or BCC) as their RoT would return a spurious
error OEMCrypto_ERROR_NOT_IMPLEMENTED. Removing the call
addresses this as well.
Bug: 190231658
Test: WV unit/integration test
Change-Id: I8216ca5a78b8c2acb5681c7f599cdc41efdf9fc7
c014da7da3