tee: amdtee: remove unused variable initialization

Remove unused variable initialization from driver code.

If enabled as a compiler option, compiler may throw warning for
unused assignments.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 757cc3e9 ("tee: add AMD-TEE driver")
Signed-off-by: Rijo Thomas <Rijo-john.Thomas@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>