greybus: connection: prevent drivers from specifying core flags

Prevent drivers from specifying core flags (currently only
GB_CONNECTION_FLAG_CONTROL) when creating connections.

Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
diff --git a/drivers/staging/greybus/connection.h b/drivers/staging/greybus/connection.h
index 7d0988e..0ea8ac8 100644
--- a/drivers/staging/greybus/connection.h
+++ b/drivers/staging/greybus/connection.h
@@ -19,6 +19,8 @@
 #define GB_CONNECTION_FLAG_CDSI1	BIT(3)
 #define GB_CONNECTION_FLAG_CONTROL	BIT(4)
 
+#define GB_CONNECTION_FLAG_CORE_MASK	GB_CONNECTION_FLAG_CONTROL
+
 enum gb_connection_state {
 	GB_CONNECTION_STATE_DISABLED		= 0,
 	GB_CONNECTION_STATE_ENABLED_TX		= 1,