Split ccm_auth function.

Move logic to ccm_starts, ccm_set_lengths, ccm_update_ad,
ccm_update and ccm_finish
Use separate variable to track context state.
Encode first block only if both mbedtls_ccm_starts() and
mbedtls_ccm_set_lengths() were called.

Signed-off-by: Mateusz Starzyk <mateusz.starzyk@mobica.com>

include/mbedtls/ccm.h

@@ -87,6 +87,9 @@ typedef struct mbedtls_ccm_context
                                                 #MBEDTLS_CCM_DECRYPT or
                                                 #MBEDTLS_CCM_STAR_ENCRYPT or
                                                 #MBEDTLS_CCM_STAR_DECRYPT. */
+    int MBEDTLS_PRIVATE(state);              /*!< Working value holding context's
+                                                  state. Used for chunked data
+                                                  input */
 }
 mbedtls_ccm_context;