fix db_subscr_ps error handling

Reset stmt and return right away on failure to execute.

Change-Id: I27e8b46915efd678c72138e250a9cbb4c9c8ac20
Fixes: Coverity Scan CID#164747
diff --git a/src/db_hlr.c b/src/db_hlr.c
index 340e7ce..f6ae18f 100644
--- a/src/db_hlr.c
+++ b/src/db_hlr.c
@@ -92,7 +92,8 @@
 	rc = sqlite3_step(stmt); /* execute the statement */
 	if (rc != SQLITE_DONE) {
 		LOGHLR(imsi, LOGL_ERROR, "Error executing SQL: %d\n", rc);
-		rc = -ENOEXEC;
+		db_remove_reset(stmt);
+		return -ENOEXEC;
 	}
 
 	rc = sqlite3_changes(dbc->db); /* verify execution result */