meta-google: host-power-control: Fix shellcheck issues

Change-Id: I9f67bc4aab9603188779c4488aef4eba6936f595
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/meta-google/recipes-google/host-power-ctrl/gpio-host-pwr/host_poweron.sh b/meta-google/recipes-google/host-power-ctrl/gpio-host-pwr/host_poweron.sh
index 2e6eb02..b115c9b 100755
--- a/meta-google/recipes-google/host-power-ctrl/gpio-host-pwr/host_poweron.sh
+++ b/meta-google/recipes-google/host-power-ctrl/gpio-host-pwr/host_poweron.sh
@@ -13,6 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# shellcheck source=meta-google/recipes-google/gpio/gpio-ctrl/lib.sh
 source /usr/share/gpio-host-pwr/lib.sh || exit
 
 gpio_build_cache 10 "$HOST_GPIO_PGOOD" "$HOST_GPIO_PWR_BTN" || exit