Fixed mixer transmission between FMU and IO

apps/px4io/i2c.c

@@ -77,7 +77,7 @@ static void		i2c_tx_complete(void);
 static DMA_HANDLE	rx_dma;
 static DMA_HANDLE	tx_dma;
 
-static uint8_t		rx_buf[64];
+static uint8_t		rx_buf[68];
 static unsigned		rx_len;
 
 static const uint8_t	junk_buf[] = { 0xff, 0xff, 0xff, 0xff };

apps/px4io/protocol.h

@@ -181,6 +181,7 @@
  * This message adds text to the mixer text buffer; the text
  * buffer is drained as the definitions are consumed.
  */
+#pragma pack(push, 1)
 struct px4io_mixdata {
 	uint16_t	f2i_mixer_magic;
 #define F2I_MIXER_MAGIC		0x6d74
@@ -191,4 +192,5 @@ struct px4io_mixdata {
 
 	char		text[0];	/* actual text size may vary */
 };
+#pragma pack(pop)