Internal renamings in PK

+ an unrelated comment in SSL

include/mbedtls/pk_internal.h

@@ -42,7 +42,7 @@ struct mbedtls_pk_info_t
     const char *name;
 
     /** Get key size in bits */
-    size_t (*get_size)( const void * );
+    size_t (*get_bitlen)( const void * );
 
     /** Tell if the context implements this type (e.g. ECKEY can do ECDSA) */
     int (*can_do)( mbedtls_pk_type_t type );