Clean up EVP_CIPHER_CTX_init() usage in cmac.c

Clean up EVP_CIPHER_CTX_init() usage in cmac.c

This replaces usage of EVP_CIPHER_CTX_init() with EVEP_CIPHER_CTX_new(),
and EVP_CIPHER_CTX_cleanup() with EVP_CIPHER_CTX_reset().

This also replaces usage of malloc with calloc, and free with freezero.

ok tb@