hostlogger.dreport: adjust shellcheck directive

Newer shellcheck also adds an SC1091 error that the 'source' fails
on.  Rather than disable shellcheck use the magic that tells shellcheck
to ignore the file (by loading from /dev/null instead).

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Iddf3ed7ae8c41cd705dc2603bc5a7b4cea006dcf
diff --git a/hostlogger.dreport b/hostlogger.dreport
index 564721c..8555fd0 100644
--- a/hostlogger.dreport
+++ b/hostlogger.dreport
@@ -4,7 +4,7 @@
 # @brief: Collect host's logs
 #
 
-# shellcheck disable=SC1090 # library comes from phosphor-debug-collector repo.
+# shellcheck source=/dev/null # library comes from phosphor-debug-collector repo.
 . "${DREPORT_INCLUDE}/functions"
 
 DESCRIPTION="Host logs"