core: Remove completion_code field from mctp_ctrl_msg_hdr

That field is only applicable for response messages, not request
messages.

Change-Id: I74d0cc206c78d162e5cd210a45d398334e1cdf52
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
diff --git a/libmctp-cmds.h b/libmctp-cmds.h
index 293aca4..80f3513 100644
--- a/libmctp-cmds.h
+++ b/libmctp-cmds.h
@@ -17,7 +17,6 @@
 	uint8_t ic_msg_type;
 	uint8_t rq_dgram_inst;
 	uint8_t command_code;
-	uint8_t completion_code;
 };
 
 #define MCTP_CTRL_HDR_MSG_TYPE	       0