DPE: Fix logging when certificate is not returned

The new_certificate_buf and new_certificate_actual_size are only valid
if the certificate is returned, so change the condition for logging them
from create_certificate to return_certificate.

Signed-off-by: Jamie Fox <jamie.fox@arm.com>
Change-Id: I7ac55f5028d56488854676a46b0e4f4051585b51
1 file changed