build: warn about RSS driver experimental status

Change-Id: I93b7afe17395a94e1ec0ae09457eb2fd320d59a9
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
diff --git a/drivers/arm/rss/rss_comms.mk b/drivers/arm/rss/rss_comms.mk
index 8f19a0b..c1c994b 100644
--- a/drivers/arm/rss/rss_comms.mk
+++ b/drivers/arm/rss/rss_comms.mk
@@ -4,6 +4,8 @@
 # SPDX-License-Identifier: BSD-3-Clause
 #
 
+$(warning "RSS driver is an experimental feature")
+
 RSS_COMMS_SOURCES	:=	$(addprefix drivers/arm/rss/,			\
 					rss_comms.c				\
 					rss_comms_protocol.c			\