basic-build-test.sh: Restore make only command

Fix local testing leftover when working on
PR 9394. This was causing basic-build-test.sh
to fail on the Open CI (not the internal one
though).

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/tests/scripts/basic-build-test.sh b/tests/scripts/basic-build-test.sh
index afaa3c7..b850147 100755
--- a/tests/scripts/basic-build-test.sh
+++ b/tests/scripts/basic-build-test.sh
@@ -76,7 +76,7 @@
 make clean
 cp "$CONFIG_H" "$CONFIG_BAK"
 scripts/config.py full
-make -j
+make
 
 
 # Step 2 - Execute the tests