meta-google: networking: fix shellcheck warnings

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I7ae5c315d5a938b29c6fd5d68f07225d125ccead
diff --git a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-lib.sh b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-lib.sh
index 7ccee8e..d3bf95d 100644
--- a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-lib.sh
+++ b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-lib.sh
@@ -128,6 +128,7 @@
 }
 
 gbmc_br_lib_init=1
-return 0 2>/dev/null
-echo "gbmc-br-lib is a library, not executed directly" >&2
-exit 1
+if ! (return 0 2>/dev/null); then
+  echo "gbmc-br-lib is a library, not executed directly" >&2
+  exit 1
+fi