fix(optee): address late comments and fix bad rc

There were some late comments to the prior change (18635) which are
address in this commit. There was also an invalid return value check
which was changed and the wrong result was being returned via the SMC
call for loading OP-TEE which is now fixed.

Signed-off-by: Jeffrey Kardatzke <jkardatzke@google.com>
Change-Id: I883ddf966662549a3ef9c801a2d4f47709422332
2 files changed