meta-ampere: shellcheck: fix up source locations

This commit fixes shelllcheck source in ampere_uartmux_ctrl.sh
to point to the exact source path.

Signed-off-by: Chau Ly <chaul@amperecomputing.com>
Change-Id: I38d92582bb7783b18ff19fb8ae5e5abe0c1e3d44
diff --git a/meta-ampere/meta-jade/recipes-ampere/platform/ampere-platform-init/ampere_uartmux_ctrl.sh b/meta-ampere/meta-jade/recipes-ampere/platform/ampere-platform-init/ampere_uartmux_ctrl.sh
index f285898..a464adc 100755
--- a/meta-ampere/meta-jade/recipes-ampere/platform/ampere-platform-init/ampere_uartmux_ctrl.sh
+++ b/meta-ampere/meta-jade/recipes-ampere/platform/ampere-platform-init/ampere_uartmux_ctrl.sh
@@ -19,7 +19,7 @@
 #        <UARTx_MODE> of 1 sets CPU To HDR_CONN
 #        <UARTx_MODE> of 2 sets BMC to CPU (eg dropbear ssh server on port 2200)
 
-# shellcheck source=/dev/null
+# shellcheck source=meta-ampere/meta-jade/recipes-ampere/platform/ampere-utils/gpio-lib.sh
 source /usr/sbin/gpio-lib.sh
 
 if [ $# -lt 2 ]; then