command: Add a command_encode_and_frame() helper

Add a helper function that calls command_encodef() followed by
command_add_frame().

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/generic/serial_irq.c

@@ -108,8 +108,7 @@ console_sendf(const struct command_encoder *ce, va_list args)
 
     // Generate message
     uint8_t *buf = &transmit_buf[tmax];
-    uint_fast8_t msglen = command_encodef(buf, ce, args);
-    command_add_frame(buf, msglen);
+    uint_fast8_t msglen = command_encode_and_frame(buf, ce, args);
 
     // Start message transmit
     writeb(&transmit_max, tmax + msglen);