[U-Boot] [PATCH v1] scripts/check-config.sh: Add usage()

[Andy Shevchenko]

When arguments are not supplied the error message is misleading and
doesn't tell what exactly has to be done.

Fix this by adding usage() and call it if above circumstance occurs.

Signed-off-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
---
 scripts/check-config.sh | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/scripts/check-config.sh b/scripts/check-config.sh
index 4848ca6e25..583f7d0963 100755
--- a/scripts/check-config.sh
+++ b/scripts/check-config.sh
@@ -17,6 +17,15 @@
 set -e
 set -u
 
+PROG_NAME="${0##*/}"
+
+usage() {
+	echo "$PROG_NAME <path to u-boot.cfg> <path to whitelist file> <source dir>"
+	exit 1
+}
+
+[ $# -ge 3 ] || usage
+
 path="$1"
 whitelist="$2"
 srctree="$3"
-- 
2.19.2