[refactoring][bssl] Move check_int_result to util module

To facilitate its reuse in other modules such as hkdf and aead
later.

Test: atest libbssl_avf_nostd.test
Bug: 302286887
Change-Id: I5373047dcd6c264eee872d46c616cd1c2b475192
diff --git a/libs/bssl/src/ec_key.rs b/libs/bssl/src/ec_key.rs
index fdd6f61..901212f 100644
--- a/libs/bssl/src/ec_key.rs
+++ b/libs/bssl/src/ec_key.rs
@@ -16,6 +16,7 @@
 //! BoringSSL.
 
 use crate::cbb::CbbFixed;
+use crate::util::check_int_result;
 use alloc::vec::Vec;
 use bssl_avf_error::{ApiName, Error, Result};
 use bssl_ffi::{
@@ -199,13 +200,4 @@
     }
 }
 
-fn check_int_result(ret: i32, api_name: ApiName) -> Result<()> {
-    if ret == 1 {
-        Ok(())
-    } else {
-        assert_eq!(ret, 0, "Unexpected return value {ret} for {api_name:?}");
-        Err(Error::CallFailed(api_name))
-    }
-}
-
 // TODO(b/301068421): Unit tests the EcKey.