Remove unused variables from tls1_change_cipher_state

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7971)

(cherry picked from commit d072eea2e39c4444ecce3598556053a4c552d9a2)