Fix missing paren to make code build

Signed-off-by: Ed Tanous <ed.tanous@intel.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
diff --git a/libmctp.h b/libmctp.h
index 4c45e51..28903d7 100644
--- a/libmctp.h
+++ b/libmctp.h
@@ -37,7 +37,7 @@
 #define MCTP_PKTBUF_BINDING_PAD	2
 
 #define MCTP_PKTBUF_SIZE	(MCTP_PKTBUF_BINDING_PAD + \
-		(sizeof(struct mctp_hdr) + MCTP_MTU)
+		(sizeof(struct mctp_hdr) + MCTP_MTU))
 
 struct mctp_pktbuf {
 	unsigned char	data[MCTP_PKTBUF_SIZE];