meta-quanta: fix new shellcheck issues

The latest version of shellcheck is stricter.  Fix a few warnings.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I7f94205aef6d348e9c53dca261ea996dd4f84a6a
diff --git a/meta-quanta/meta-gbs/recipes-google/acpi-power-state/acpi-power-state-daemon/gbs-set-boot-failsafe.sh b/meta-quanta/meta-gbs/recipes-google/acpi-power-state/acpi-power-state-daemon/gbs-set-boot-failsafe.sh
index 6580fbe..822200b 100644
--- a/meta-quanta/meta-gbs/recipes-google/acpi-power-state/acpi-power-state-daemon/gbs-set-boot-failsafe.sh
+++ b/meta-quanta/meta-gbs/recipes-google/acpi-power-state/acpi-power-state-daemon/gbs-set-boot-failsafe.sh
@@ -30,6 +30,6 @@
 }
 
 # Exit without running main() if sourced
-return 0 2>/dev/null
-
-main "$@"
+if ! (return 0 2>/dev/null); then
+    main "$@"
+fi