BUG-2386: ISIS Yang model compilation issue

This patch fixes a slight typo, which prevents the resulting Pattern from being useful.

Change-Id: Ib4bc98ad68237ebea4eccf5522dfd79db88a7906
Signed-off-by: Reinaldo Penno <rapenno@gmail.com>
(cherry picked from commit 980409656693d454ad12e438d6c9ecd764ebd7c1)
Merge "BUG-2386: ISIS Yang model compilation issue" into stable/helium