sanity-check: set shellcheck level to warning

This patch locks shellcheck severity level to "warning". All "info"
level messages will be ignored.

Signed-off-by: Milosz Wasilewski <milosz.wasilewski@oss.qualcomm.com>
diff --git a/sanity-check.sh b/sanity-check.sh
index 1a2fa3e..9af667d 100755
--- a/sanity-check.sh
+++ b/sanity-check.sh
@@ -4,7 +4,8 @@
 python3 validate.py \
     -r build-error.txt \
     -p E501 W503 E203 \
-    -s SC1091 SC2230 SC3043
+    -s SC1091 SC2230 SC3043 \
+    -l warning
 
 # pycodestyle checks skipped:
 # E501: line too long
@@ -18,3 +19,5 @@
 # Reason: 'which' is widely used and supported. And 'command' applets isn't
 # available in busybox, refer to https://busybox.net/downloads/BusyBox.html
 # SC2230: which is non-standard. Use builtin 'command -v' instead.
+
+# "warning" is the default severity level for shellcheck
diff --git a/validate.py b/validate.py
index bac8cbf..aa44eb1 100755
--- a/validate.py
+++ b/validate.py
@@ -221,7 +221,7 @@
     return 0
 
 
-def validate_shell(filename, ignore_options):
+def validate_shell(filename, args):
     ignore_string = ""
     if args.shellcheck_ignore is not None:
         # Exclude types of warnings in the following format:
@@ -229,6 +229,7 @@
         ignore_string = "-e %s" % ",".join(args.shellcheck_ignore)
     if len(ignore_string) < 4:  # contains only "-e "
         ignore_string = ""
+    ignore_string = "-S %s %s" % (args.shellcheck_level, ignore_string)
     cmd = "shellcheck %s" % ignore_string
     return validate_external(cmd, filename, "SHELLCHECK", args)
 
@@ -342,6 +343,14 @@
         dest="shellcheck_ignore",
     )
     parser.add_argument(
+        "-l",
+        "--shellcheck-level",
+        default="warning",
+        help="Shellcheck level set with -S",
+        dest="shellcheck_level",
+    )
+
+    parser.add_argument(
         "-g",
         "--git-latest",
         action="store_true",