Makefile: Add missing semicolon after 'unsupported' message

Make it bail out instead of printing "exit 1".

Change-Id: I58c00eb7faa661351b1f00e477f0e8ccc08854a3
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/73444
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/Makefile b/Makefile
index 92f5901..ec4537f 100644
--- a/Makefile
+++ b/Makefile
@@ -962,7 +962,7 @@
 		exit 1;								\
 	fi
 	@if [ "$(UNSUPPORTED_FEATURES)" ]; then					\
-		echo "The following features are unavailable on your machine: $(UNSUPPORTED_FEATURES)" \
+		echo "The following features are unavailable on your machine: $(UNSUPPORTED_FEATURES)"; \
 		exit 1;								\
 	fi