[qca-nss-drv] Fix proc return values

Fix proc return values, so sysctl can have proper userspace errors

CRs-fixed: 836854

Change-Id: I5103f1a6d3e97b55fdad3550270c08a8acaffe88
Signed-off-by: Thomas Wu <wthomas@codeaurora.org>
diff --git a/nss_ipv6.c b/nss_ipv6.c
index 3257624..d46e4f7 100644
--- a/nss_ipv6.c
+++ b/nss_ipv6.c
@@ -390,7 +390,7 @@
 	}
 
 	up(&i6cfgp.sem);
-	return NSS_SUCCESS;
+	return 0;
 
 failure:
 	/*
@@ -398,7 +398,7 @@
 	 */
 	nss_ipv6_conn_cfg = i6cfgp.current_value;
 	up(&i6cfgp.sem);
-	return NSS_FAILURE;
+	return -EINVAL;
 }
 
 static ctl_table nss_ipv6_table[] = {