greybus: use protocol_id for numeric values

Switch to using "protocol_id" to refer to a byte-sized numeric
protocol number.  A "protocol" will represent a protocol structure
(created in the next patch).

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
diff --git a/drivers/staging/greybus/greybus_manifest.h b/drivers/staging/greybus/greybus_manifest.h
index c18ee11..c6988ce 100644
--- a/drivers/staging/greybus/greybus_manifest.h
+++ b/drivers/staging/greybus/greybus_manifest.h
@@ -98,13 +98,13 @@
 /*
  * A CPort descriptor indicates the id of the interface within the
  * module it's associated with, along with the CPort id used to
- * address the CPort.  The protocol defines the format of messages
+ * address the CPort.  The protocol id defines the format of messages
  * exchanged using the CPort.
  */
 struct greybus_descriptor_cport {
 	__u8	interface;
 	__le16	id;
-	__u8	protocol;	/* enum greybus_protocol */
+	__u8	protocol_id;	/* enum greybus_protocol */
 };
 
 /*