tls: in AES-CBC code, do not set key for every record - do it once

function                                             old     new   delta
aes_setkey                                            16     212    +196
tls_handshake                                       1941    1977     +36
aes_encrypt_1                                        382     396     +14
xwrite_encrypted                                     605     604      -1
tls_xread_record                                     659     656      -3
aes_encrypt_one_block                                 65      59      -6
aes_cbc_encrypt                                      172     121     -51
aesgcm_setkey                                         58       -     -58
aes_cbc_decrypt                                      958     881     -77
KeyExpansion                                         188       -    -188
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 3/5 up/down: 246/-384)         Total: -138 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/tls_aes.h b/networking/tls_aes.h
index fc38817..e9e3721 100644
--- a/networking/tls_aes.h
+++ b/networking/tls_aes.h
@@ -10,5 +10,5 @@
 
 void aes_encrypt_one_block(struct tls_aes *aes, const void *data, void *dst) FAST_FUNC;
 
-void aes_cbc_encrypt(const void *key, int klen, void *iv, const void *data, size_t len, void *dst) FAST_FUNC;
-void aes_cbc_decrypt(const void *key, int klen, void *iv, const void *data, size_t len, void *dst) FAST_FUNC;
+void aes_cbc_encrypt(struct tls_aes *aes, void *iv, const void *data, size_t len, void *dst) FAST_FUNC;
+void aes_cbc_decrypt(struct tls_aes *aes, void *iv, const void *data, size_t len, void *dst) FAST_FUNC;