RT2848: Remove extra NULL check
RT2848: Remove extra NULL check

Don't need to check auth for NULL since we did when we
assigned to it.

Reviewed-by: Emilia Kasper <6521fc25e7624eef7c3a0d89b71de7e612d27d37@openssl.org>

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl